MODEL PAPER - 2 [2026] — Science STD 10 — Question

Metals X and Y can be recovered from the anode mud left behind after the electrolytic refining of copper metal. The coins made of metal X look new even after several years of use but the coins made of metal Y lose their shine gradually and get blackened soon. When metal X is alloyed with a small amount of metal Y, it becomes hard and hence suitable for making ornaments. What are metals X and Y ? Also state the colour of metal X.

Write the balanced chemical equations for the following reaction.
Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogencarbonate.

Explain the given reaction with the example:

Hydrogenation reaction.

How does the atomic size vary on going down from top to bottom in a group of the periodic table? Why does it vary this way?

Draw the electron-dot structure of a hydrogen chloride molecule:

1. Which inert gas does the H atom in HCl resemble in electron arrangement?
2. Which inert gas does the Cl atom in HCl resemble in electron arrangement?

Which of the following will conduct electricity and which not?
MgCl₂, CCl₄, NaCl, CS₂, Na₂S Give reasons for your choice.

Describe one reaction of a carboxylic acid.

Why do HCl, HNO₃, etc. show acidic characters in aqueous solutions while solutions while solutions of compounds like alcohol and glucose do not show acidic character?

Why are carbon and its compounds used as fuels for most applications?

Why should curd and other sour foodstuffs (like lemon juice, etc.) not be kept in metal containers (such as copper and brass vessels)?