Science : Ch 01 – Chemical Reactions and Equations

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

What type of reaction is represented by: A + BC → AC + B ?

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

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

Identify the reducing agent in the following reactions: 2H₂ + O₂ → 2H₂O

When hydrogen sulphide gas is passed through a blue solution of copper sulphate, the colour of the solution fades and a black precipitate is obtained.Why does the colour of the solution fades?

Mention whether it is a physical or chemical changes: -Evaporation of petrol

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

Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during the electrolysis of water is:

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:

One of the following processess doesnot require a chemical 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.

Which among the following is (are) double displacement reaction(s)?

1. Pb + CuCl₂ → PbCl₂ + Cu
2. Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
3. C + O₂ → CO₂
4. CH₄ + 2O₂ → CO₂ + 2H₂O

Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of reaction involved?

1. Displacement reaction
2. Precipitation reaction
3. Combination reaction
4. Double displacement reaction