Combination Reaction

Q.

Give examples of combination reactions.

Q.

When hydrogen in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical changes involved in the two cases.

Q.

Give an example of a combination reaction between two elements.

Q.

To get her house whitewashed, an officer bought 10 kg of quicklime from the market and dissolved in 30 litres of water.
She noticed that the water started boiling even when it was not being heated.
Choose the corresponding product formed and the type of reaction involved.

1. Product formed:- Slaked lime
   Type of reaction:- Exothermic
2. Product formed:- Limestone
   Type of reaction:- Exothermic
3. Product formed:- Limestone
   Type of reaction:- Endothermic
4. Product formed:- Limewater
   Type of reaction:- Endothermic

Q. What is a combination reaction? Give two examples.

Q. What are exothermic and endothermic reactions? Give examples.

Q.

Which gives carbon dioxide on heating slaked lime or limestone?

Q. $H_2\left(g\right)+F_2\left(g\right)\to 2\mathrm{HF}\left(g\right)+\mathrm{heat}$

This reaction is an example of:
i. Combination reaction
ii. Endothermic reaction
iii. Exothermic reaction

1. (i) and (iii)
2. (i) and (ii)
3. Only (i)

Q. Define combination reaction. Give an example of a combination reaction that is also exothermic.

Q. Identify the combination reactions among the following:

1. $2C_8{H}_{18}+25O_2\to$
   $16C{O}_2+18H_{2}O$
2. $8Fe+S_8\to 8FeS$
3. $MgO+C{O}_2\to MgC{O}_3$
4. $3Pb(N{O}_3{)}_2+2AlC{l}_3\to$
   $3PbC{l}_2+2Al(N{O}_3{)}_3$

Q. Identify the general representation of a combination reaction.

1. $\text{A+B}\to \text{AB}$
2. $\text{A+B}\to \text{B+C}$
3. $\text{AB}\to \text{A+B}$
4. $\text{A+B+C}\to \text{X+Y}$

Q. Give reasons: ​
Hydrogen is collected by the downward displacement of water and not of air, even though it is lighter than air.​

Q.

Ice, water, and water vapor are chemically the same but they display different ___ properties.

Q. Which of the following reaction types are true for the given reaction?

$\text{C(s)}+{\text{O}}_2\text{(g)}\to {\text{CO}}_2\text{(g)}+\text{Heat}$

1. Combination reaction
2. Decomposition reaction
3. Endothermic reaction
4. Exothermic reaction

Q.

When ammonia gas reacts with hydrogen chloride, which state of matter is the product in?

1. Gaseous state

2. Liquid state

3. Plasma

4. Solid state

Q.

Identify the component which when mixed with water, shows Tyndall effect.
(A) Sugar
(B) Vinegar
(C) Copper sulphate
(D) Paint

Q.

Crystals having fixed number of water molecules are known as

1. Anhydrous substances

2. hydrated substances

3. deliquescent substances

4. hygroscopic substances

Q. Which of the following is commonly known as quicklime?

1. Calcium hydroxide
2. Calcium oxide
3. Carbon dioxide
4. Sodium oxide

Q.

Do correct the given incorrect statement “Hygroscopic substances absorb water and change their state”.

Q. Which of the following metal comes below copper in reactivity series?

1. Iron
2. Zinc
3. Aluminium
4. Silver

Q.

Give one example of non-aqueous solution.

Q.

When hydrogen in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical changes involved in the two cases.

Q.

Which of the following are examples of combination reactions?

(i) $CaO+O_2\to 2CaC{O}_3$

(ii) $CaC{O}_3\to CaO+C{O}_2$

(iii) $MgO+C{O}_2\to MgC{O}_3$

(iv) $Fe+S\to FeS$

(v) $2AgCl+sunlight\to 2Ag+C{l}_2$

(vi) $C{H}_4+2O_2\to C{O}_2+2H_{2}O$

(vii) $N{a}_{2}O+H_{2}O\to 2NaOH$

1. (ii), (vii), (iv), (vi)

2. (i), (ii), (v), (vii)

3. (ii), (iii), (iv), (vi)

4. (i), (iii), (iv), (vii)

Q.

In the type of reaction called ___ two compounds exchange their positive and negative radicals.

Q. Carbon reacts with oxygen to give carbon dioxide. This is an example of:
[1 mark]
A. Displacement reaction
B. Double displacement reaction
C. Decomposition reaction
D. Combination reaction

Q.

Mention the differences between exothermic and endothermic changes.

Q. Which of the following will show the “Tyndall effect”?
A) Sugar solution B) Milk
C) Kerosene in water

Q. Identify the most reactive metal among the following.

1. Gold
2. Copper
3. Potassium
4. Iron

Q. $2Na\left(s\right)+S\left(s\right)\stackrel{Fuse}{\to }N{a}_{2}S\left(s\right)$

1. Neutrallization reaction
2. Synthesis reaction
3. Precipitation reaction
4. Combination reaction

Q.

The reaction between iron filings and sulphur powder is an example of _______ .

1. Decomposition reaction

2. Combination reaction

3. Endothermic reaction

4. Redox reaction