Conditions Necessary for Chemical Reactions to Occur

Q.

When mercuric chloride and potassium iodide are___ in a mortar to produce mercuric iodide.

1. Mixed

2. Heated

3. Ignited

4. Crushed

Q. State the main characteristics of chemical reactions. Give at least one example in each case. [4 marks]

Q.

Acidulated water decomposes when subjected to ___.

1. Electric current

2. Sunlight

3. Thermal Energy

4. Sound Energy

Q.

$2HgO\left(s\right)\stackrel{X}{\to }2Hg\left(l\right)+O_2\left(g\right)$

What is ${}^{\prime }{X}^{\prime }$ in the equation?

1. Sound Energy

2. Heat/Thermal Energy

3. Electric Current

4. Sunlight

Q. Upward arrow in a chemical equation represents _________.

1. heat absorbed
2. formation of a precipitate
3. heat released
4. evolution of a gas

Q. What are the factors affecting chemical reactions?

1. Concentration
2. Colour
3. Particle size
4. Temperature
5. Surface area
6. Odour
7. Pressure
8. Catalyst

Q.

What is known as the energy required to start a chemical reaction?

1. Activation energy

2. Yield point

3. Start point

4. Mercalis point

Q. Close contact between reactants is required for a chemical reaction to happen.

1. True
2. False

Q.

When does chlorine water decompose to hydrochloric acid?

1. None Of the above.

2. When exposed to light

3. When mixed with oxygen

4. When a catalyst acts on them