Chemical Reactions (Viva Voce) : Class 9 : Chemistry : Amrita Online Lab

Chemical Reactions

	1)	A student added a few pieces of zinc into dil.H₂SO₄ taken in a test tube. Suddenly, evolution of gas occurs. What gas is evolved?
		H₂ SO₂ SO₃ O₂

	2)	Which product is formed when magnesium burns in air?
		MgCO₃ MgO Mg(OH)₂ MgH₂

	3)	Why do copper sulphate crystals change colour from blue to white on heating?
		Due to hydration Due to hydrogenation Due to dehydrogenation Due to dehydration

	4)	While performing an experiment, a student adds sodium sulphate solution to a colourless solution. A white precipitate is immediately formed and is insoluble in dil. HCl. The colourless solution is …………………………… & the precipitate formed is……………………
		KCl & NaCl CH₃COOH & CH₃COONa BaCl₂ & BaSO₄ MgCl₂ & NaCl

	5)	When will we observe a precipitate to occur in the solution?
		Barium chloride is added to sodium sulphate. Barium chloride is added to sodium chloride. Sodium sulphate is added to sodium chloride. Hydrochloric acid is added to barium chloride.

	6)	Barium sulphate is:
		Soluble in water. Partially soluble in water. Insoluble in water. A gas at room temperature.

	7)	What is observed when burning a magnesium ribbon in air?
		A greenish gas is obtained. It burns brightly, giving out a golden colour. It burns brightly, leaving blue ash. It burns brightly, leaving behind white powder.

	8)	What happens when blue litmus is added to a water extract of MgO?
		It turns red. It becomes colourless. It turns green. No change is observed.

	9)	Why does iron displace copper from its salt solution?
		Both Fe and Cu are equally reactive. Fe is less reactive than Cu. Fe is more reactive than Cu. None of the above.

10)

Which diagram shows the safest method to detect hydrogen gas produced in a reaction?

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