English Medium कक्षा १० - CBSE Important Questions for Science

When a potassium iodide solution is added to a solution of lead (II) nitrate in a test tube, a precipitate is formed.

List two types of reactions in which this reaction can be placed.

A student mixes sodium sulphate powder in barium chloride powder. What change would the student observe on mixing the two powders? Justify your answer and explain how he can obtain the desired change.

Give reasons for the following:
The reaction of iron (III) oxide [Fe₂O₃] with heated aluminum is used to join cracked machine parts.

Why do we store silver chloride in a dark coloured bottle?

In the redox reaction:

MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂

Which of the following is the correct observation of the reaction shown in the above set up?

These consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:

Assertion: Silver bromide decomposition is used in black and white photography.

Reason: Light provides energy for this exothermic reaction.

Identify the types of reaction mentioned above. Give one example for type in the form of a balanced chemical equation.

Identify the types of reaction mentioned above. Give one example for type in the form of a balanced chemical equation.

1. Identify the gasses evolved at the anode and cathode in the above experimental set up.
2. Name the process that occurs. Why is it called so?
3. Illustrate the reaction of the process with the help of a chemical equation.

To balance the following chemical equation the value of x and y should respectively be:

\[\ce{2NaOH + xAl_2O_3->yNaAlO_2 + H_2O}\]

A metal nitrate 'A' on heating gives a metal oxide along with evolution of a brown coloured gas 'B' and a colourless gas, which helps in burning. Aqueous solution of 'A' when reacted with potassium iodide forms a yellow precipitate.

1. Identify 'A' and 'B'
2. Name the types of the reactions involved in the above statement.

A reddish brown metal used in electrical wires when powdered and heated strongly turns black. When hydrogen gas is passed over this black substance, it regains its original colour. Based on this information answer the following questions:

1. Name the metal and the black substance formed.
2. Write balanced chemical equations for the two reactions involved in the above information

State the change in colour observed in following case mentioning the reason:

A piece of zinc is dipped in ferrous sulphate solution.

State the change in colour observed in following case mentioning the reason:

Copper powder is strongly heated in air.

A student took a small amount of copper oxide in a conical flask and added dilute hydrochloric acid to it with constant stirring. He observed a change in colour of the solution. 

1. Write the name of the compound formed and its colour.
2. Write a balanced chemical equation for the reaction involved.

Identify the product which represents the solid state in the above reaction.

The colour of the solution observed after 30 minutes of placing zinc metal in copper sulphate solution is ______.

Dil. HCl is added to Zn granules. How will you prove that chemical change has taken place here? Support your response with two arguments.

A chemical reaction in which exchange of ions occurs between the reactants is known as ______.