English Medium Class 10 - CBSE Important Questions

Identify the substances that are oxidised and the substances that are reduced in the following reaction.

\[\ce{CuO_{(s)} + H2_{(g)} -> Cu_{(s)} + H2O_{(l)}}\]

Complete the following equation:
CH₄ + O₂ —>

Complete the following equation:

CH₂ + H₅OH `("Hot Conc." H_2SO_4)/`>

Complete the following equation:

CH₃COOH + NaOH → 

A student weighed some raisins and recorded the weight as ‘x’. She then soaked the raisins in distilled water. After about 2 hours she removed the raisins, wiped them dry and weighed them again, and recorded that as ‘y’. The percentage of water absorbed by raisins may be determined using the relationship.

In the experiment for determining the percentage of water absorbed by raisins, we do the final weighing of the raisins after keeping them dipped in water for about one hour. For the accuracy of the result, the extra water from the surface of the soaked raisins is removed by

The aqueous solutions of copper sulphate and zinc sulphate appear

(A) blue and green respectively

(B) green and colourless respectively

(C) blue and brown respectively

(D) blue and colourless respectively.

Solutions of copper sulphate, iron sulphate and zinc sulphate are prepared and marked I, II and III respectively. Few pieces of aluminium are added to each solutions. After some time a change will be observe in

(A) I and II

(B) II and III

(C) III and I

(D) All the three

To determine the percentage of water absorbed by raisins, raisins are soaked in water for: 

Raisins are wiped off gently before final weighing with the help of

The step(s) necessary for determining the percentage of water absorbed by raisins is/are:

The colour of an aqueous solution of zinc sulphate as observed in the laboratory is:

(1) Green 

(2) Yellow 

(3) Blue 

(4) Colourless

To show that zinc is a more active metal than copper, the correct procedure is to: 

(1) add dilute nitric acid on strips of both the metals. 

(2) observe transmission of heat through strips of zinc and copper. 

(3) prepare solution of zinc sulphate and hang strip of copper into it. 

(4) prepare solution of copper sulphate and hang strip of zinc into it. 

In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?

(i) What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?
(ii) What type of reaction is this?
(iii) Write a balanced chemical equation to represent the above reaction.

Show the formation of Na2O by the transfer of electrons. 

(a) Design an activity to demonstrate the decomposition reaction of lead nitrate.

(b) Draw labelled diagram of the experimental set-up. List two main observations.

(c) Write balanced chemical equation for the reaction stating the physical state of the reactant and the products.

What is observed after about 1 hour of adding the strips of copper and aluminium separately to the ferrous sulphate solution filled in two beakers? Name the reaction if any change in colour is noticed. Also, write a chemical equation for the reaction.

A student wants to study a decomposition reaction by taking ferrous sulphate crystals. Write two precautions he must observe while performing the experiment. 

Identify the type of reaction taking place of the following case and write the balanced chemical equation of the reaction:
Zinc reacts with silver nitrate to produce zinc nitrate and silver.