Most insect bites cause a stinging sensation because of the injection of a weak acid into the surface of the skin. Which substance could be used to neutralise the acid from an insect bite?
| substance | pH |
A | battery acid | 1 |
B | toothpaste | 8 |
C | grill cleaner | 13 |
D | lime juice | 3 |
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Calcium reacts with sulfuric acid to form the salt, calcium sulfate, and another product.
What is the other product?
Oxygen
Hydrogen
Water
Carbon dioxide
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Which words complete the gaps 1 & 2 in these sentences?
Aqueous solutions of acids contain 1 ions and aqueous solutions of alkalis contain 2 ions.
| 1 | 2 |
A | Na+ | OH– |
B | OH– | H+ |
C | H+ | Cl– |
D | H+ | OH– |
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Indicators are substances that change colour when they are added to acidic or alkaline solutions.
Indicator | Colour in acid | Colour in alkali |
methyl orange | red | orange |
litmus | red | blue |
thymolphthalein | blue | colourless |
universal indicator | green | purple |
Which indicator displays the correct colour in each solution?
Methyl orange
Litmus
Thymolphthalein
Universal indicator
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A student is provided with an unmarked beaker containing a colourless solution and asked to identify it. The student decides to perform a series of reactions with the solution and record the observations.
Which of these observations is not indicative of an acid?
The solution causes blue litmus to turn red.
On heating and the addition of copper oxide, the solution turns blue.
On the addition of ammonium carbonate, a colourless, pungent gas is released.
On the addition of a piece of magnesium, effervescence was produced and the magnesium piece ‘disappeared’ after a few minutes.
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Which of the following statements is not correct?
Ammonia is released when a base reacts with an ammonium salt.
Neutralisation occurs when an acid and an alkali react together.
Carbon dioxide is released when an acid and a carbonate react together.
The higher the pH of a solution, the higher its acidity.
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Which of the following properties is not indicative of a base?
Carbon dioxide is released when it reacts with a carbonate.
A salt is formed on reaction with an acid.
Ammonia is released on reaction with an ammonium salt.
Universal indicator paper turns blue when placed in an alkaline solution.
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A student was given an unknown substance and asked to analyse it. The student decided to perform three tests and recorded the results as shown below.
1 | On heating with ammonium chloride a gas is released. |
2 | The substance turns methyl orange yellow. |
3 | The substance does not react with potassium carbonate. |
What kind of substance was the student given?
A salt
A metal
A base
An acid
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A student is testing two substances, P and Q, as shown.
The results of the test are that the Universal indicator paper turns blue. What are substances P and Q?
HCl and NH4NO3
NaOH and NH4NO3
NaCO3 and HCl
NaCO3 and NaOH
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A student gradually added excess potassium hydroxide from a burette to a conical flask containing sulfuric acid as part of a rate of reaction investigation.
Which statement describes the change in pH of the sulfuric acid as the aqueous potassium hydroxide was added?
The pH decreases from 14 to neutrality and remains constant
The pH decreases from 12 to 2
The pH increases from 1 to neutrality and remains constant
The pH increases from 1 to around 13
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Which row shows the pH values for 0.1 mol / dm3 solutions of ammonia, hydrochloric acid, sodium chloride and sodium hydroxide?
| pH values | |||
| NH3 | HCl | NaCl | NaOH |
A | 1 | 7 | 13 | 11 |
B | 7 | 1 | 11 | 13 |
C | 11 | 1 | 7 | 13 |
D | 13 | 11 | 7 | 1 |
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The water in a lake is acidic and the fish are dying. The water in the lake needs to be neutralised.
Which compound can be added in excess to neutralise the water in the lake?
calcium carbonate
phosphoric acid
potassium hydroxide
sodium nitrate
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Which statement about weak acids is correct?
They are partially dissociated in aqueous solution.
They do not react with alkalis.
They do not react with metals.
They form solutions with pH values in the range 0 to 2.
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A colourless aqueous solution of pH 13 is tested separately with methyl orange indicator and thymolphthalein indicator.
Which row is correct?
| colour with methyl orange | colour with thymolphthalein |
A | red | blue |
B | red | colourless |
C | yellow | blue |
D | yellow | colourless |
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Ionic equations 1 and 2 show how substance X behaves in aqueous solution.
1 | X- + H+ → XH |
2 | X → X- + H+ |
Which row correctly describes substance X?
| acid | base |
A | 1 | 1 |
B | 1 | 2 |
C | 2 | 2 |
D | 2 | 1 |
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In a reaction rate experiment, a student used equal volumes of acids P and Q to react with excess magnesium in separate conical flasks.
The following observations were recorded:
1 | Acid P produces hydrogen gas faster than acid Q |
2 | Both gases produce the same total volume of hydrogen gas |
Which statement correctly explains the students observations?
Acid P has a higher pH than acid Q
P is a carboxylic acid
Q is a weaker acid than P
P is more concentrated than Q
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Which indicator displays the correct colour in each solution?
Indicator | Colour in dilute sulfuric acid | Colour in potassium hydroxide solution |
methyl orange | red | yellow |
universal indicator | red | orange |
litmus | red | purple |
thymolphthalein | blue | colourless |
Methyl orange
Universal indicator
Litmus
Thymolphthalein
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Which equation does not show the correct reaction of an acid?
CuO + 2HCl → CuCl2 + H2O
CaCO3 + 2HNO3 → Ca(NO3)2 + CO2 + H2
2KOH + H2SO4 → K2SO4 + 2H2O
Zn + H2SO4 → ZnSO4 + H2
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1 markThe pH of two samples of different dilute acids were found.
Acid X had a pH of 6
Acid Y had a pH of 3
Which statement is correct?
The hydrogen ion concentration of acid X is 1000 times greater than acid Y
The hydrogen ion concentration of acid Y is 3 times greater than acid X
The hydrogen ion concentration of acid Y is 1000 times greater than acid X
The hydrogen ion concentration of acid X is 100 times greater than acid Y
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