Science : Ch 01 – Chemical Reactions and Equations

Give an example of decomposition reaction taking place in our body.

What happens when sodium sulphate solution is added to barium chloride solution?

Why are anti-oxidants added to fat and oil containing food items?

Identify the reducing agent in the following reactions: 2H₂O + 2F₂ → 4HF + O₂

Mention whether it is physical or chemical changes : Heating of an iron rod to red hot

State the reactions are exothermic or endothermic in nature: Decomposition of ferrous sulphate

In the electrolysis of water, name the gases liberated at cathode

Solid calcium oxide reacts vigorously with water to form calcium hydroxide, accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form a solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?

1. It is an endothermic reaction
2. It is an exothermic reaction.
3. The pH of the resulting solution will be more than seven.
4. The pH of the resulting solution will be less than seven

When copper turning are added to silver nitrate solution, a blue coloured solution is formed after some time. It is because copper ?

The following reaction is used for the preparation of oxygen gas in the laboratory: 2KClO₃(s) Heat ⎯ → Catalyst ⎯⎯⎯ 2KCl(s) + 3O₂(g) Which of the following statement(s) is/are correct about the reaction?

One of the following does not happen during a chemical reaction.

You are given the solution of lead nitrate. In order to obtain a yellow precipitate you should blend with it a solution of:

Dilute hydrochloric acid is added to granulated zinc taken in a test tube. The following observations are recorded. Designate the accurate observation:

Calcium oxide reacts vigorously with water to produce slaked lime. CaO(s) + H₂O(l) → Ca(OH)₂(aq) This reaction can be classified as:

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

Three beakers labelled as A, B and C, each containing 25 ml of water, were taken. A small amount of NaOH, anhydrous CuSO4 and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in the case of beaker C, the temperature of the solution fell. Which one of the following statement(s) is (are) correct?

1. In beakers A and B, exothermic process has occurred.
2. In beakers A and B, endothermic process has occurred
3. In beaker C, exothermic process has occurred
4. In beaker C, endothermic process has occurred.