Class 10th Chemistry Board Exam Preparation

A student tests a sample of rainwater and finds its pH to be 5.5. Which of the following conclusions is most likely correct regarding this rainwater sample?

• It is highly acidic and will corrode metals quickly.

• It is slightly acidic but safe for drinking.

• It is basic and will neutralize acids.

• It is neutral and will not react with acids or bases.

To prevent food from turning rancid, it is often packaged in bags flushed with nitrogen gas. Which of the following properties of nitrogen gas is most important for this purpose?

• Nitrogen is colorless.

• Nitrogen is odorless.

• Nitrogen is unreactive.

• Nitrogen is lighter than air.

A metal 'X' reacts with dilute hydrochloric acid to produce hydrogen gas and a salt 'XCl₂'. Metal 'X' could be:

• Na

• Al

• Ag

• Zn

A solution turns red litmus blue. If we add acid to this solution drop by drop, what would you observe?

• The solution will remain blue.

• The solution will become colorless and then turn red.

• The solution will turn purple and then red.

• The solution will directly turn red.

Calcium oxide reacts vigorously with water. This reaction is exothermic. Which of the following practices utilizes this property of calcium oxide in daily life?

• Using calcium oxide to neutralize acidic soil in agriculture.

• Using calcium oxide for white washing buildings.

• Using calcium oxide as a drying agent in labs.

• All of the above.

Consider sodium chloride (NaCl) and methane (CH₄). Which of the following statements correctly compares their properties?

• NaCl has a high melting point and is a good conductor in solid state; CH₄ has a low melting point and is a poor conductor.

• NaCl has a low melting point and is a poor conductor; CH₄ has a high melting point and is a good conductor.

• NaCl has a high melting point and is a good conductor in molten state; CH₄ has a low melting point and is a poor conductor.

• NaCl has a low melting point and is a good conductor in molten state; CH₄ has a high melting point and is a poor conductor.

If you add a piece of copper metal to a solution of zinc sulphate, what would you expect to observe?

• Copper metal will dissolve and zinc metal will be deposited.

• Zinc metal will dissolve and copper metal will be deposited.

• No reaction will occur.

• A vigorous reaction with evolution of hydrogen gas will occur.

A compound 'A' reacts with sodium metal to liberate hydrogen gas. Compound 'A' could be:

• CH₃CH₂CHO

• CH₃COCH₃

• CH₃CH₂CH₂OH

Why are copper wires used for electrical wiring, while copper vessels are not used for storing strong acid solutions?

• Copper is a good conductor of electricity but reacts with strong acids.

• Copper is a poor conductor of electricity but does not react with strong acids.

• Copper is expensive and hence used only where conductivity is essential.

• Copper is easily available in wire form but not in vessel form.

Which of the following represents the correct order of acidic strength?

• H₂O < CH₃COOH < HCl

• HCl < CH₃COOH < H₂O

• CH₃COOH < H₂O < HCl

• H₂O < HCl < CH₃COOH