50.0 mL of tap water was taken in a beaker. Hydrochloric acid was added drop by drop to water. The temperature and pH of the solution was noted. The following graph was obtained. Choose the correct statements related to this activity.

(i) The process of dissolving an acid in water is highly endothermic.

(ii) The pH of the solution increases rapidly on addition of acid.

(iii) The pH of the solution decreases rapidly on addition of acid.

(iv) The pH of tap water was around 7.0.

1. (i) and (ii)
2. (i) and (iii)
3. (iii) and (iv)
4. (ii) and (iv)

A student, took four metals P, Q, R and S and carried out different experiments to study the properties of metals. Some of the observations were :

• All metals could not be cut with a knife except metal R.
• Metal P combined with oxygen to form an oxide M₂O₃ which reacted with both acids and bases.
• Reaction with water.
  
  • P – Did not react either with cold or hot water but reacted with steam
  • Q – Reacted with hot water and the metal started floating
  • R – Reacted violently with cold water.
  • S – Did not react with water at all

Based on the above observations answer the following:

Out of the given metals, the one which needs to be stored under Kerosene is

1. P
2. R
3. S
4. Q

A student, took four metals P, Q, R and S and carried out different experiments to study the properties of metals. Some of the observations were :

• All metals could not be cut with a knife except metal R.
• Metal P combined with oxygen to form an oxide M₂O₃ which reacted with both acids and bases.
• Reaction with water.
  
  • P – Did not react either with cold or hot water but reacted with steam
  • Q – Reacted with hot water and the metal started floating
  • R – Reacted violently with cold water.
  • S – Did not react with water at all

Based on the above observations answer the following:

Metal which forms amphoteric oxides is

1. P
2. Q
3. R
4. S

A student, took four metals P, Q, R and S and carried out different experiments to study the properties of metals. Some of the observations were :

• All metals could not be cut with a knife except metal R.
• Metal P combined with oxygen to form an oxide M₂O₃ which reacted with both acids and bases.
• Reaction with water.
  
  • P – Did not react either with cold or hot water but reacted with steam
  • Q – Reacted with hot water and the metal started floating
  • R – Reacted violently with cold water.
  • S – Did not react with water at all

Based on the above observations answer the following:

The increasing order of the reactivity of the four metals is;

1. P < Q < R < S
2. S < R < Q < P
3. S < P < Q < R
4. P < R < Q < S