English Medium Class 10 - CBSE Important Questions for Science

Write the chemical equation for the following reaction:
Cinnabar is heated in the presence of air.

Write the chemical equation for the following reaction:
Manganese dioxide is heated with aluminum powder.

Keerti added dilute Hydrochloric acid to four metals and recorded her observations as shown in the table given below:

Select the correct observation(s) and give chemical equation(s) of the reaction involved.

Why is acidified water considered to be a good conductor of electricity?

Write a chemical equation showing the ionic products formed on dissolving potassium hydroxide in water.

On adding dilute sulphuric acid to a test tube containing a metal ‘X’, a colourless gas is produced when a burning match stick is brought near it. Which of the following correctly represents the metal ‘X’?

State any four characteristics of a homologous series

Write the number of covalent bonds in the molecule of butane, C₄H₁₀.

Write three different chemical reactions showing the conversion of ethanoic acid to sodium ethanoate. Write balanced chemical equation in each case. Write the name of the reactants and the products other ethanoic acid and sodium ethanoate in each case.

A carbon compound 'P' on heating with excess conc. H₂SO₄ forms another carbon compound 'Q' which on addition of hydrogen in the presence of nickel catalyst forms a saturated carbon compound 'R'. One molecule of 'R' on combustion forms two molecules of carbon dioxide and three molecules of water. Identify P, Q and R and write chemical equations for the reactions involved

A student puts a drop of reaction mixture of a saponification reaction first a blue litmus paper and then on a red litmus paper. He may observe that:

(a) There is no change in the blue litmus paper and the red litmus paper turns white.

(b) There is no change in the red litmus paper and the blue litmus paper turns red.

(c) There is no change in the blue litmus paper and the red litmus paper turns blue.

(d) No change in colour is observed in both the litmus papers

A student adds a spoon full of powdered sodium hydrogen carbonate to a flask containing ethanoic acid. List two main observations, he must note in his note book, about the reaction that takes place. Also write chemical equation foe the reaction.

Write the next homologue of the following: C₂H₄

Write the next homologue of the following: C₄H₆

Name the compound formed when ethanol is heated in excess of conc. sulphuric acid at 443 K. Also, write the chemical equation of the reaction stating the role of conc. sulphuric acid in it. What would happen if hydrogen is added to the product of this reaction in the presence of a catalyst such as palladium or nickel?

Classify the following carbon compounds into two homologous series and name them.

C₃H₄, C₃H₆, C₄H₆, C₄H₈, C₅H₈, C₅H₁₀

Write the name and formula of the 2nd member of homologous series having general formula C_nH_2n.

Write the name and formula of the 2nd member of homologous series having general formula C_nH_{2n + 2}.

Write the name and formula of the 2nd member of homologous series having general formula C_nH_{2n – 2}.

What are esters ?