Title: icma02
Course: Phil's test course

Q: This is a Combined question.

Here is a molecule [Image: Acetic acid]

Complete the following table

colour | element | number present
grey | [[element:selectmenu:2]] | [[ccount:numeric:__2__]]
white | [[element:selectmenu:1]] | [[hcount:numeric:__2__]]
red | [[element:selectmenu:4]] | [[ocount:numeric:__2__]]

What is the molecular formula? [[formula:pmatch]]

How is this formula normally rearranged and shown so as to convey meaning about the structure? [[condensed:pmatch]]

What is the name of the compound? [[name:pmatch]]
A: 2; ?; 2; 4; match (C_2H_4O_2); match (CH_3COOH|CH_3CO_2H); match (ethanoic|acetic acid)
Feedback: The correct answers are colour | element | number present | group in periodic table grey | carbon | 2 | 4 white | hydrogen | 4 | 1 red | oxygen | 2 | 6 The molecular formula is C_2H_4O_2, but CH_3COOH indicates to experienced readers that this is ethanoic acid (common name acetic acid).

Q: This is a Short answer question.

There are three different ways of increasing the rate of a chemical reaction. Two of them are

- to increase the temperature
- to increase the concentration of one or more of the reactants.

What is the third way?
A: add*catalyst* / use*catalyst*
Feedback ("add*catalyst*"): Your answer is correct.
Feedback ("use*catalyst*"): Your answer is correct.
Feedback ("*catalyst*"): Your answer appears to be on the right lines but perhaps you could phrase it differently.
Feedback (any other answer): Your answer is incorrect.
Feedback: The rate of a chemical reaction can be increased by any of - adding a catalyst - increasing the temperature - increasing the concentration of one or more of the reactants.
  Hint: Every chemical reaction has an energy barrier that must be overcome before reactant molecules can form products. One way to increase the rate is to lower this barrier. How might you achieve this?
  Hint: You will find more on lowering the energy barrier in Block 8 Section 10.5. Perhaps you would care to read that now before trying again.

Q: This is a Pattern match question.

The photograph shows a layer of oil floating on top of a glass of water. Why does the oil float?

[Image: Oil on water]

Please give your answer as a short phrase or sentence.
- match_all ( match_mow (great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg) not ( match_mw (water|not|higher) ) ) (Your answer is incorrect. (Rule 10))
- match_all ( match_any ( match_mw (great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg than_water) match_mw (dens*|[specific gravity]|sg great*|high|higher|more|bigger|heavier|heavy than_water) match_mw (dens* water < dens* oil) ) not ( match_w (than_oil) ) ) (Your answer is incorrect. (Rule 11) The oil does not float because it is more dense than the water.)
- match_any ( match_mow (it|its|it's|oil|0il_great*|high|higher|more|bigger|heavier|heavy_dens*|[specific gravity]|sg*) match_mw (it|its|it's|oil|0il_dens*|[specific gravity]|sg_great*|high|higher|more|bigger|heavier|heavy) ) (Your answer is incorrect. (Rule 12) The oil does not float because it is more dense than the water.)
- match_all ( match_any ( match_mow (oil|it|its|it's great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg) match_mrxow (oil|it|its|it's_denser) match_mow (oil|it|its|it's not_less*|low* dens*|[specific gravity]|sg) ) not ( match_mw (water) ) ) (Your answer is incorrect. (Rule 13) The oil does not float because it is more dense than the water.)
- match_any ( match_mw (oil|it|its|it's great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg than water) match_mrxwp1 (oil|it|its|it's_denser than water) match_mwp0 (oil|it|its|it's not_less*|low*|light* dens*|[specific gravity]|sg than water) ) (Your answer is incorrect. (Rule 14) The oil does not float because it is more dense than the water.)
- match_any ( match_mw (oil|it|its|it's_great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg) match_mw (oil|it|its|it's_dens*|[specific gravity]|sg_great*|high|higher|more|bigger|heavier|heavy) ) (Your answer is incorrect. (Rule 15) The oil does not float because it is more dense than the water.)
- match_all ( match_mow (less*|smaller|low*|light* dens*|[specific gravity]|sg) not ( match_mw (water|not|higher) ) ) (Your answer is correct. (Rule 19))
- match_any ( match_mw (less*|smaller|low*|light* dens*|[specific gravity]|sg than water*) match_mw (dens*|[specific gravity]|sg less*|smaller|low*|light* than water) match_mw (isn't|not_dens*|[specific gravity]|sg as_water) match_mw (dens*|[specific gravity]|sg oil < dens*|[specific gravity]|sg water) ) (Your answer is correct. (Rule 20))
- match_all ( match_any ( match_mow (water great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg) match_mrxow (water denser) ) not ( match_mw (oil|oils|not) ) ) (Your answer is correct. (Rule 23))
- match_any ( match_mw (water great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg than oil) match_mw (dens*|[specific gravity]|sg water great*|high|higher|more|bigger|heavier|heavy than oil) match_mrxw (water denser than oil) match_mow (water_denser oil_floats) ) (Your answer is correct. (Rule 24))
- match_any ( match_mw (water|[water_is]_great*|high|higher|more|bigger|heavier|heavy_dens*|[specific gravity]|sg) match_mw (water_dens*|[specific gravity]|sg|[same volume]_great*|high|higher|more|bigger|heavier|heavy) match_mw (water same volume great*|high|higher|more|bigger|heavier|heavy) ) (Your answer is correct. (Rule 25))
- match_all ( match_any ( match_mw (oil 920* water 1000*|[1 000*]) match_mw (water 1000*|[1_000*] oil 920*) match_mw (oil 920* less) match_mw (water 1000*|[1_000*] more|greater) ) match_mwp4 (density|[mass_cubic|ml|m3|volume]) ) (Your answer is correct. (Rule 26))
- match_any ( match_mwp0 (less*|smaller|low*|light* dens*|[specific gravity]|sg than_oil) match_mwp0 (dens*|[specific gravity]|sg less*|smaller|low*|light* than_oil*) ) (Your answer is incorrect. (Rule 31))
- match_any ( match_mw (water_less*|smaller|low*|light*_dens*|[specific gravity]|sg) match_mw (water_dens*|[specific gravity]|sg_less*|smaller|low*|light*) ) (Your answer is incorrect. (Rule 32))
- match_any ( match_mw (mass oil|oils|it|its|per less*|smaller|low*|light* same|equiv*|per volume|size|amount|ml water) match_mw (mass oil|oils less*|smaller|low*|light* [water per|same metre|ml|litre|vol*]|[per|same metre|ml|litre|vol* water]) ) (Your answer is correct. (Rule 45))
- match_any ( match_mw (oil|oils|it|its mass [less*|smaller|low*|light* same|equiv*|per volume|size|amount|ml]|[same|equiv*|per volume|size|amount|ml|litre less*|smaller|low*|light*] water) match_mw (oil|oils|it|its mass less*|smaller|low*|light* same|equiv*|per|equal volume|size|amount|ml|quantity water) match_mw (oil|oils|it|its less*|smaller|low*|light* mass same|equiv*|per volume|size|amount|ml water) ) (Your answer is correct. (Rule 46))
- match_any ( match_mw ([oil|oils|it|its|it's_mass|weight]|[mass|weight_oil] less*|smaller|low*|light* water displace*|replac*) match_mw (oil|oils|it|its_less*|smaller|low*|light*_mass|weight water displace*) ) (Your answer is correct. (Rule 47))
- match_any ( match_mw (oil|oils|it|its less*|smaller|low*|light* water same volume|size) match_mw (oil|oils|it|its less*|smaller|low*|light* cubic metre water) match_mw (oil|oils|it|its volume less*|smaller|low*|light* mass) ) (Your answer is correct. (Rule 50))
- match_any ( match_mw (less*|smaller|low*|light* dens* floats) match_mw (great*|high|higher|more|bigger|heavier|heavy dens* sinks) match_mw (oil|oils|it|its less*|smaller|low*|light* cubic metre water) match_mw (mass cubic metre water greater) ) (Your answer is correct. (Rule 51))
- match_any ( match_mw (light*_same_volume_water) match_mw (lighter water replac*|displac*) match_mw (water replac*|displac* heav*|[greater_mass]) ) (Your answer is correct. (Rule 61))
- match_any ( match_mw (dens*|[specific gravity]|sg) ) (Your answer is incorrect. (Rule 71) You are right to say that the reason the oil floats has something to do with density, but you need to word your answer more carefully. The oil floats for the same reason that ice floats on water. See Section 4.2.1)
- match_all ( match_mw (mass|weight) not ( match_mw (density|[specific gravity]|sg) ) ) (Your answer is incorrect. (Rule 80) The reason that the oil floats has something to do with its mass, but you need to be more specific. The oil floats for the same reason that ice floats on water. See Section 4.2.1)
- match_all ( match_mw (light*) not ( match_mw (water) ) ) (Your answer is incorrect. (Rule 81) The reason that the oil floats has something to do with its mass, but you need to be more specific. The oil floats for the same reason that ice floats on water. See Section 4.2.1)
- match_mw (it|its|it's|oil_lighter) (Your answer is incorrect. (Rule 82) The reason that the oil floats has something to do with its mass, but you need to be more specific. The oil floats for the same reason that ice floats on water. See Section 4.2.1)
- match_any ( match_mw (it|its|it's|oil_float*) match_mw (light* than water) match_mw (water heavier|sink*) ) (Your answer is incorrect. (Rule 73) It is true that the water sinks to the bottom of the glass whilst the oil floats, but why is this? It is for the same reason that ice floats on water. See Section 4.2.1.)
- not ( match_mw (dens&|[specific gravity]|sg) ) (Your answer is incorrect. (Rule 89))
- match_any ( match_mow (mix|mixing|imiscible|hydrophobic|insoluble) match_mow (*n't|not_soluble|dissolve) ) (Your answer is incorrect. (Rule 74))
- * (Your answer is incorrect. (Rule 99))
A: match_all ( match_mow (less*|smaller|low*|light* dens*|[specific gravity]|sg) not ( match_mw (water|not|higher) ) ) / match_any ( match_mw (less*|smaller|low*|light* dens*|[specific gravity]|sg than water*) match_mw (dens*|[specific gravity]|sg less*|smaller|low*|light* than water) match_mw (isn't|not_dens*|[specific gravity]|sg as_water) match_mw (dens*|[specific gravity]|sg oil < dens*|[specific gravity]|sg water) ) / match_all ( match_any ( match_mow (water great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg) match_mrxow (water denser) ) not ( match_mw (oil|oils|not) ) ) / match_any ( match_mw (water great*|high|higher|more|bigger|heavier|heavy dens*|[specific gravity]|sg than oil) match_mw (dens*|[specific gravity]|sg water great*|high|higher|more|bigger|heavier|heavy than oil) match_mrxw (water denser than oil) match_mow (water_denser oil_floats) ) / match_any ( match_mw (water|[water_is]_great*|high|higher|more|bigger|heavier|heavy_dens*|[specific gravity]|sg) match_mw (water_dens*|[specific gravity]|sg|[same volume]_great*|high|higher|more|bigger|heavier|heavy) match_mw (water same volume great*|high|higher|more|bigger|heavier|heavy) ) / match_all ( match_any ( match_mw (oil 920* water 1000*|[1 000*]) match_mw (water 1000*|[1_000*] oil 920*) match_mw (oil 920* less) match_mw (water 1000*|[1_000*] more|greater) ) match_mwp4 (density|[mass_cubic|ml|m3|volume]) ) / match_any ( match_mw (mass oil|oils|it|its|per less*|smaller|low*|light* same|equiv*|per volume|size|amount|ml water) match_mw (mass oil|oils less*|smaller|low*|light* [water per|same metre|ml|litre|vol*]|[per|same metre|ml|litre|vol* water]) ) / match_any ( match_mw (oil|oils|it|its mass [less*|smaller|low*|light* same|equiv*|per volume|size|amount|ml]|[same|equiv*|per volume|size|amount|ml|litre less*|smaller|low*|light*] water) match_mw (oil|oils|it|its mass less*|smaller|low*|light* same|equiv*|per|equal volume|size|amount|ml|quantity water) match_mw (oil|oils|it|its less*|smaller|low*|light* mass same|equiv*|per volume|size|amount|ml water) ) / match_any ( match_mw ([oil|oils|it|its|it's_mass|weight]|[mass|weight_oil] less*|smaller|low*|light* water displace*|replac*) match_mw (oil|oils|it|its_less*|smaller|low*|light*_mass|weight water displace*) ) / match_any ( match_mw (oil|oils|it|its less*|smaller|low*|light* water same volume|size) match_mw (oil|oils|it|its less*|smaller|low*|light* cubic metre water) match_mw (oil|oils|it|its volume less*|smaller|low*|light* mass) ) / match_any ( match_mw (less*|smaller|low*|light* dens* floats) match_mw (great*|high|higher|more|bigger|heavier|heavy dens* sinks) match_mw (oil|oils|it|its less*|smaller|low*|light* cubic metre water) match_mw (mass cubic metre water greater) ) / match_any ( match_mw (light*_same_volume_water) match_mw (lighter water replac*|displac*) match_mw (water replac*|displac* heav*|[greater_mass]) )
Feedback: The oil floats because its density is less than that of the water, where $$density = \frac{mass}{volume}$$ See Section 4.2.1.
  Hint: The oil floats for the same reason that ice floats on water.
  Hint: See Section 4.2.1. Have another go, remembering to express your answer as a simple phrase or sentence.

Q: This is a Drag and drop onto images question.

Identify the features in this cross-section by dragging the labels into the boxes.

Use the mouse to drag the boxed words into the empty boxes. Alternatively, use the tab key to select an empty box, then use the space key to cycle through the options.
- Zone 1 | mountain belt
- Zone 2 | continental shelf
- Zone 3 | ocean trench
- Zone 4 | abyssal plain
- Zone 5 | continental slope
- Zone 6 | continental rise
- Zone 7 | island arc
- Zone 8 | mid-ocean ridge
Feedback: The locations are now labelled on the diagram below. [Image: labelled ocean floor] More information about the major features of the Earth's surface can be found in Block 3, Section 6.2.
  Hint: Incorrect placements will be removed.
  Hint: - The abyssal plain is a flat almost featureless expanse of ocean floor 4km to 6km below sea-level. - The continental rise is the gently sloping part of the ocean floor beyond the continental slope. - The continental shelf is the gently sloping ocean floor just offshore from the land. - The continental slope is the relatively steep part of the ocean floor beyond the continental shelf. - A mid-ocean ridge is a broad submarine ridge several kilometres high. - A mountain belt is a long range of mountains. - An island arc is a chain of volcanic islands. - An oceanic trench is a deep trough in the ocean floor.

Q: This is a Drag and drop markers question.

Please place the markers on the map of Milton Keynes to show the OU and all railway stations that are on the West Coast main line.
- Zone 1 | OU
- Zone 2 | Railway station
- Zone 3 | Railway station
- Zone 4 | Railway station
Feedback: The Open University is at the junction of Brickhill Street and Groveway. There are three railway stations on the West Coast main line, Wolverton, Milton Keynes Central and Bletchley. Bow Brickhill and Woburn Sands stations are on what remains of the old Oxford - Cambridge 'Universities line'.
  Hint: You should be looking to place four markers on the map.
  Hint: You should be looking to place markers on three railway stations.

This short assessment showcases the question types that are available for use in interactive with multiple tries mode in Moodle 2.5

Numeric input | Text input | Selection questions | 2D | Multiple input
Q1 Numerical | Q6 Pattern match | Q8 Drag and drop into text | Q15 Drag and drop markers | Q17 Combined
Q2 & Q3 Variable numeric | Q7 Short answer | Q9 Drag and drop onto images | Q16 Pattern match with JME | Mathematical input
Q4 Variable numeric sets |  | Q10 Matching |  | Q18 STACK
Q5 Variable numeric sets with units |  | Q11 Multiple choice |  | External
 |  | Q12 Multiple response |  | Q19 OpenMark
 |  | Q13 Select missing words |  |
 |  | Q14 True/false |  |

The rubric that precedes each of these categories explains a little more about the possibilities and constraints offered by each question type within the category.

Questions are marked one by one when you press 'Check' and in all cases other than the True/False question you are allowed up to three tries should you not give a correct answer.

As this is a formative assessment designed for you to learn about Moodle's facilities, you are allowed to make multiple attempts at the whole assessment.

Click on 'Next' to move to the next screen. Alternatively you may move directly to individual questions by clicking on the corresponding numbers in the Questions navigation panel. You may end the assessment at any point by clicking on 'Finish attempt...' which will lead you to a Summary page from where you may 'Submit' your answers and finish.

Information screens such as this appear in the Questions panel as an 'i'.

Q: This is a Drag and drop into text question.

Drag and drop the words from the list below to fill the blank spaces and correctly complete the sentence.

At 25°C all aqueous basic solutions have [...] ion concentrations less than [...]
mol litre^-1 and pH values [...] than [...].

Use the mouse to drag the boxed words into the empty boxes. Alternatively, use the tab key to select an empty box, then use the space key to cycle through the options.
Also offered: positive; hydroxide; negative; 107; 1; less
A: hydrogen; 10-7; greater; 7
Feedback: At 25 °C all aqueous basic solutions have hydrogen ion concentrations less than 10^−7 mol litre^−1 and pH values greater than 7. See Section 9 of S103 Discovering Science Block 8.
  Hint: You may wish to read Section 9 of Discovering Science Block 8.
  Hint: Any incorrect choices will be removed before your final try.

Numeric response

The first group of questions require a numeric response.There are a variety of question types in Moodle that may be used:

Q1 Numerical: the original Moodle numeric question type

Q2 Variable numeric: allows calculations using variables within the question and the values of the variables may be generated randomly. The student response may be requested in Scientific notation and to a set number of significant figures. Response checks for incorrect rounding and 'power of ten' errors are available. Sequences of Variable numeric questions can be specified to use the same random numbers.

Q3 and Q4 Variable numeric sets: as for Variable numeric but restricted to pre-specified sets of values for the variables. Question 4 shows that sequences of Variable numeric sets questions can use the same dataset.

Q5 Variable numeric sets with units: for those scientists and mathematicians who like units to be included with calculations.

Please note that the STACK and Combined question types shown later in this demonstration also support the assessment of numerical answers.

All question types may show properly formatted mathematics using the mathematics filter which will accept TeX or MathML.

The questions perform validity checks on the response before accepting it, for example non-numeric characters are not allowed (scientific notation excepted).

Text response

The second group of questions require a textual response. There are two question types in Moodle that may be used:

Q6 Pattern match: has a dictionary, easy specification of synonyms and sophisticated response matching features. This is the recommended question type for handling free text responses.

Q7 Short answer: is the original Moodle question for handling textual responses and has very limited response matching features.

Questions requiring a response in two dimensions

The fourth group requires students to respond in two dimensions. The first question type uses positional information, the second requires a molecular structure

Q15 Drag and drop markers: multiple markers are used to identify features on an image.

Q16 Pattern match with JME: students use the Java Molecular Editor to draw their response as a molecular structure.

Selection questions

The third group of questions require students to select their response from a variety of choices which should contain plausible distractors. There are a variety of selection question types in Moodle:

Q8 Drag and drop into text: the drag items are words

Q9 Drag and drop onto images: pre-defined locations on an image must be labelled with words or small images

Q10 Matching: answers have to be matched to questions

Q11 Multiple choice: choose one from many

Q12 OU multiple response: choose many from many

Q13 Select missing words: similar to Drag and drop into text but uses drop-down lists

Q14 True/false: choose one from two

Questions that enable the marking of more sophisticated mathematical input

STACK (System for Teaching and Assessment using a Computer algebra Kernel) questions are created and/or marked with the help of the Maxima Computer Algebra System.

Q18 STACK questions bring a level of mathematical sophistication to both the setting of questions and marking of student responses.

Questions that enable multiple inputs

Q17 Combined questions are constructed from multiple sub-questions which may be numeric (based on variable numeric), pattern match, multiple response (based on OU multiple response) and select missing words.

Q: This is a Select missing words question.

The following text comes from a Hong Kong guidebook, but is shown here split into clauses. For each clause select a label from the list to identify the form of the verb.

It is said [...] that the animal year originated [...] when Buddha commanded all the beasts of the earth [...] to assemble before him [...]. The names of the years were established according to the first twelve animals' order of arrival [...]. There's no cat year [...] as the rat tricked the cat [...] into arriving late [...]. Your Chinese zodiac sign is based on the year of your birth [...]. Being born or married in a particular year [...] is believed [...] to determine one's fortune [...] so in this era of modern birth-control techniques, Chinese parents often plan for their children's sign [...]. The year of the dragon (2000) sees the biggest jump in the birth rate [...], closely followed by the year of the tiger (1998) [...].
A: finite - present tense; finite - past tense; finite - past tense; non-finite - infinitive; finite - past tense; finite - present tense; finite - past tense; non-finite - ing participle; finite - present tense; non-finite - ing participle; finite - present tense; non-finite - infinitive; finite - present tense; finite - present tense; non-finite - ed/en participle
Feedback: The correct label for each clause is as follows It is said [finite - present tense] that the animal year originated [finite - past tense] when Buddha commanded all the beasts of the earth [finite - past tense] to assemble before him [non-finite - infinitive]. The names of the years were established according to the first twelve animals' order of arrival [finite - past tense]. There's no cat year [finite - present tense] as the rat tricked the cat [finite - past tense] into arriving late [non-finite - -ing participle]. Your Chinese zodiac sign is based on the year of your birth [finite - present tense]. Being born or married in a particular year [non-finite - -ing participle] is believed [finite - present tense] to determine one's fortune [non-finite - infinitive] so in this era of modern birth-control techniques, Chinese parents often plan for their children's sign [finite - present tense]. The year of the dragon (2000) sees the biggest jump in the birth rate [finite - present tense], closely followed by the year of the tiger (1998) [non-finite - -ed/en participle].
  Hint: When you press 'Try again' any incorrect choices will be removed.

External questions

The final group demonstrates how Moodle can incorporate questions that are provided by other question engines. Here we show just one OpenMark feature that is unavailable in Moodle. Other OpenMark features are illustrated at www.open.ac.uk/openmarkexamples.

Q19 OpenMark: This OpenMark question has five variants and five available images. One variant is chosen at runtime and the image is chosen to match. The response requires two numeric inputs in a mathematical construct - a fraction.

Q: This is a Multiple choice question.

Estimate the gradient of the curve shown in the plot at x = 2.

[Image: Curve]

Click on the answer closest to your estimate.
- 1 (This value is too low.)
- 2 (This value is too low.)
- 3 (This value is too low.)
- 4 (The gradient is indeed 4.)
- 5 (This value is too high.)
- 6 (This value is too high.)
A: 4
Feedback: [Image: Curve with tangent] Gradient of tangent = $$\frac{\Delta y}{\Delta x} = \frac{14 - 0}{4.0 - 0.5} = \frac{14}{3.5} = 4.0$$ The gradient of a curve at any point is the same as the gradient of a tangent drawn at that point, so the gradient of the curve is 4.0 at x = 2.
  Hint: Start by imagining a tangent drawn against the curve at x = 2. Your tangent should be exactly parallel to the curve at x = 2.
  Hint: Where does your tangent, drawn at x = 2, cross the x and y axes? Estimate these points then calculate the gradient as the difference in y values divided by the difference in x values.

Q: This is a Matching question.

Listed below are seven quantities together with a list of units on the right. From the drop-down lists choose the appropriate units for each quantity.
- electric charge | coulomb
- electric current | amp
- energy | joule
- force | newton
- power | watt
- temperature | kelvin
- voltage difference | volt
Also offered: einstein; pascal
If right: Your answer is fully correct. Well done.
Feedback: Here are the quantities, in alphabetical order, together with their units. electric charge | coulomb electric current | amp energy | joule force | newton power | watt temperature | kelvin voltage difference | volt
  Hint: If in doubt do consult a reference book.
  Hint: Perhaps you would care to refer to Block 5 of Discovering Science. When you select Try again any incorrect selections that you have made will be cleared.

Q: This is a Numerical question.

Solve $$x^2 + 3x - 28 = 0$$

Enter either of the possible answers.
A: -7 / 4
Feedback ("-7"): Your answer is correct.
Feedback ("4"): Your answer is correct.
Feedback (any other answer): Your answer is incorrect.
Feedback: The quadratic equation is $$\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ a = 1, b = 3 and c = -28. $$x = \frac{-3 \pm \sqrt{3^2 - 4\times 1\times(-28)}}{2\times a}$$ $$x = \frac{-3 \pm \sqrt{9 + 112}}{2}$$ $$x = \frac{-3 \pm \sqrt{121}}{2}$$ $$x = \frac{-3 \pm 11}{2}$$ $$x = \frac{-14}{2}$$ or $$\frac{8}{2}$$ and the solutions are x = -7 and x = 4. We can prove these are correct by substituting the values into the original equation. $$(-7)^2 + 3\times(-7) - 28 = 49 - 21 - 28 = 0$$ $$4^2 + 3\times4 - 28 = 16 + 12 -28 = 0$$
  Hint: You may need to be reminded of the quadratic formula $$\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
  Hint: You will need to substitute for a, b and c in the quadratic formula $$\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ a is the coefficient for $$x^2$$, b is coefficient for $$x$$ and c is the constant.

Q: This is an OU multiple response question.

Which four of the following expressions are equivalent to $$4y$$?
- $$\frac{2y+6y}{2}$$
- $$4\frac{y^2}{y}$$
- $$\frac{1}{2}(2y+6y)$$
- $$2(y+y)$$
- $$2y+\frac{6y}{2}$$
- $$\frac{2y^2}{y}$$
- $$\sqrt{16}y^2$$
- $$6(y-2)$$
A: $$\frac{2y+6y}{2}$$ / $$4\frac{y^2}{y}$$ / $$\frac{1}{2}(2y+6y)$$ / $$2(y+y)$$
Feedback: The following four expressions may all be simplified to $$4y$$: $$\frac{2y+6y}{2}$$ = $$\frac{8y}{2}$$ = $$4y$$; $$4\frac{y^2}{y}$$ = $$4y$$ $$\frac{1}{2}(2y+6y)$$ = $$\frac{1}{2}8y$$ = $$4y$$; $$2(y+y)$$ = $$2(2y)$$ = $$4y$$; The other four expressions simplify to give the following: $$2y+\frac{6y}{2}$$ = $$2y+3y$$ = $$5y$$; $$\frac{2y^2}{y}$$ = $$2y$$ $$\sqrt{16}y^2$$ = $$4y^2$$; $$6(y-2)$$ = $$6y - 12$$
  Hint: Start by expanding all the expressions to remove the brackets.
  Hint: For your final attempt any incorrect choices that you have made will be removed.

Q: This is a Variable numeric question

Evaluate the following. You should give your answer in scientific notation and to one significant figure. You may choose to do the calculation with or without a calculator.

Keyboard users may use ↑ (the up arrow key) to enter superscript mode and ↓ (the down arrow key) to return to normal.

$$ \frac{\sqrt{[[a]] \times 10^{[[c]]}}}{[[b]] \times 10^{-[[d]]} \times 10^5} $$ = ______
- 1.0e9 (Your answer is correct.)
- b (Look carefully at the positioning of the square root sign.)
- * (Your answer is incorrect.)
A: 1.0e9
Feedback: $$ \frac{\sqrt{[[a]] \times 10^{[[c]]}}}{[[b]] \times 10^{-[[d]]} \times 10^5} $$ | = $$ \frac{[[b]] \times 10^{[[ee]]}}{[[b]] \times 10^{-[[d]] + 5}} $$ | = $$ \frac{1 \times 10^{[[ee]]}}{10^{[[f]]}} $$ | = $$1 \times 10^9 $$
  Hint: Hint 1.
  Hint: Hint 2.

Q: This is a Variable numeric sets question.

What is [[a]] ÷ −[[b]]? _____
- c (Your answer is correct.)
- -c (Your answer is incorrect. You appear to have divided [[a]] by [[b]] instead of dividing [[a]] by minus [[b]].)
- d (Your answer is incorrect. You appear to have added [[a]] and −[[b]] instead of dividing [[a]] by −[[b]].)
- e (Your answer is incorrect. You appear to have added [[a]] and [[b]] instead of dividing [[a]] by −[[b]].)
- f (Your answer is incorrect. You appear to have multiplied [[a]] and [[b]] instead of dividing [[a]] by minus [[b]].)
- * (Your answer is incorrect.)
A: c
Feedback: [[a]] ÷ −[[b]] = −$$\frac {[[a]]} {[[b]]} $$ = [[c]]
  Hint: Hint 1
  Hint: Hint 2

Q: This is a Pattern match with JME question.

Vinegars, from malt vinegars, through wine vinegars to fruit vinegars are widely used for seasoning food, either as straight vinegars or with oil as vinaigrettes. Vinegars are dilute solutions of acetic acid produced by the fermentation of alcohols.

You probably use vinegars regularly but can you draw the chemical structure of acetic acid?
- match (CC\(=O\)O) (Your answer is correct.)
- * (Your answer is incorrect.)
A: match (CC\(=O\)O)
Feedback: The systematic name for acetic acid is ethanoic acid, CH_3COOH. This is represented by the structural formula [Image: acetic acid] which when hydrogens are added is [Image: acetic acid]
  Hint: Is it any help to know that the systematic name is ethanoic acid?

Q: This is a True/false question.

The vibration frequency of the O_2 molecule is higher than that of the HF molecule.
- True (Your answer is incorrect.)
- False (Your answer is correct.)
A: False
Feedback: O_2 contains a double bond, but the lighter molecule HF contains a single bond. The effects of mass and bond strength are acting in opposite senses and it is not easy to predict the answer. Higher vibrations involving hydrogen are typically at higher frequency than other vibrations. The vibrational numbers are O_2 = 1556 cm^-1 HF = 3958 cm^-1

Q: This is a Variable numeric sets with units question.

A solution is made by dissolving [[mass]] g of potassium chlorate in 100 g water at 90 ºC. The solution is then cooled to 10 ºC. What mass of crystals is deposited? Give your answer to the nearest whole number and include the correct unit. ________ | [Image: solubility curve]
- precipitate (Your numeric answer is correct.)
- * (Your numeric answer is incorrect.)
A: precipitate
Feedback: A saturated solution of potassium chlorate at 10 ºC contains 5 g per 100 g water. This means that [[mass]] g – 5 g = [[precipitate]] g are deposited.
  Hint: .
  Hint: From the graph read off the concentration of a saturated solution at 10 ºC. Then subtract this from the value of the initial concentration.

Q: This is a Variable numeric sets question that uses the same numeric values as the previous question.

As these two questions show, it is possible to ask a series of variable numeric sets questions on the same dataset.

What is [[a]] + −[[b]]? _____
- c (Your answer is correct.)
- -c (Your answer is incorrect. You appear to have added minus [[a]] and [[b]] instead of adding [[a]] and minus [[b]].)
- d (Your answer is incorrect. You appear to have divided [[a]] by −[[b]] instead of adding [[a]] and −[[b]].)
- e (Your answer is incorrect. You appear to have divided [[a]] by [[b]] instead of adding [[a]] and −[[b]].)
- f (Your answer is incorrect. You appear to have multiplied [[a]] and [[b]] instead of adding [[a]] and minus [[b]].)
- * (Your answer is incorrect.)
A: c
Feedback: [[a]] + −[[b]] = [[c]]