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If copper is kept open in the air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of (a) CuSO4 (b) CuCO3 (c) Cu(NO3 ) 2 (d) CuO

Answer: (b) CuCO3 Copper forms a green deposit on its surface when exposed to air which is usually a mixture of copper carbonate and copper... View Article

Stainless steel is a very useful material for our life. In stainless steel, iron is mixed with (a) Ni and Cr (b) Cu and Cr (c) Ni and Cu (d) Cu and Au

Answer: (a) Ni and Cr Stainless steel is an alloy of Iron, Nicker and chromium. This alloy makes the metal strong, durable and... View Article

Galvanisation is a method of protecting iron from rusting by coating with a thin layer of (a) Gallium (b) Aluminium (c) Zinc (d) Silver

Answer: (c) Zinc Galvanizing is a process in which iron or steel is coated with a thin layer of zinc to protect them from corrosion.... View Article

Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining? (i) Au (ii) Cu (iii) Na (iv) K (a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (iii) and (iv)

Answer: (a) (i) and (ii) The metals obtained by various reduction processes are not very pure. They contain impurities that must be eliminated... View Article

Which of the following metals exist in their native state in nature? 1) Cu 2) Au 3) Zn 4) Ag (a) (i) and (ii) (b) (ii) and (iii) (c) (ii) and (iv) (d) (iii) and (iv)

Answer: (c) (ii) and (iv) Gold and silver are non-reactive metals and they exist in the native state of nature. Metals at the bottom of the... View Article

Which one of the following properties is not generally exhibited by ionic compounds? (a) Solubility in water (b) Electrical conductivity in solid-state (c) High melting and boiling points (d) Electrical conductivity in a molten state

Answer: (b) Electrical conductivity in solid-state NaCl and other ionic compounds have a high melting and boiling point. They are more soluble in... View Article

Which of the following are not ionic compounds? (i) KCl (ii) HCl (iii) CCl4 (iv) NaCl (a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (d) (i) and (iii)

Answer: (b) (ii) and (iii) HCl and CCl4 are covalent compounds; hence they cannot be ionic. Covalent bonding are found in non-ionic substances.... View Article

The composition of aqua-regia is (a) Dil.HCl: Conc. HNO3 3: 1 (b) Conc.HCl: Dil. HNO3 3 : 1 (c) Conc.HCl: Conc.HNO3 3 : 1 (d) Dil.HCl: Dil.HNO3 3: 1

Answer: (c) Conc.HCl : Conc.HNO3 3 : 1 Aqua regia is a yellow-orange or sometimes red colour fuming liquid. Aqua regia is a mixture of nitric... View Article

Generally, metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)? (a) H2 SO4 (b) HCl (c) HNO3 (d) All of these

Answer: (c) HNO3 Hydrogen gas is not evolved when a metal reacts with nitric acid because nitric acid is a strong oxidizing agent; it oxidizes... View Article

What happens when calcium is treated with water? (i) It does not react with water (ii) It reacts violently with water (iii) It reacts less violently with water (iv) Bubbles of hydrogen gas formed stick to the surface of calcium (a) (i) and (iv) (b) (ii) and (iii) (c) (i) and (ii) (d) (iii) and (iv)

(d) (iii) and (iv) In the case of calcium, the interaction with water is less violent, and hydrogen begins to float on the surface of the water,... View Article

Which of the following oxide(s) of iron would be obtained on the prolonged reaction of iron with steam? (a) FeO (b) Fe2O3 (c) Fe3O4 (d) Fe2O3 and Fe3O4

Answer: (c) Fe3O4 The chemical equation for the reaction of iron with steam can be written as 3Fe(s) + 4H2O → Fe3O4 + H2 Iron + Water →... View Article

Which one of the following metals does not react with cold as well as hot water? (a) Na (b) Ca (c) Mg (d) Fe

Answer: (d) Fe Sodium, calcium, and magnesium are metals that are strongly reactive to water and form hydroxides. Iron is a less reactive metal... View Article

Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same? (i) Good thermal conductivity (ii) Good electrical conductivity (iii) Ductility (iv) High melting point (a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (i) and (iv)

Answer: (d) (i) and (iv) Aluminium is ductile and has a high electrical conductivity, which makes it unsuitable for utensil production.... View Article

The ability of metals to be drawn into thin wires is known as (a) ductility (b) malleability (c) sonorousity (d) conductivity

Answer: (a) ductility Metals are minerals or substances that form naturally below the surface of the Earth. Most metals are lustrous or shiny.... View Article

Which of the following property is generally not shown by metals? (a) Electrical conduction (b) Sonorous in nature (c) Dullness (d) Ductility

Answer: (c) Dullness Metals are minerals or substances that form naturally below the surface of the Earth. Most metals are lustrous or shiny.... View Article

Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.

Answer: (1) 2NaOH + Zn → Na2ZnO2 + H2(g) (2) NaOH + HCl → NaCl + H2O (3) NaOH + CH3COOH → CH3COONa + H2O By the following... View Article

A sulphate salt of Group 2 element of the Periodic Table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in the open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt, and why does it show such behaviour? Give the reaction involved.

Answer: The sulphate salt should be calcium sulphate which is white and soft substance. Calcium sulphate is popularly known as plaster of... View Article

A dry pellet of a common base B, when kept in the open absorbs moisture and turns sticky. The compound is also a by-product of the chloralkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution.

Answer: A compound which is a byproduct of the chloralkali process is NaOH. Hence compound B is NaOH. When NaOH is treated with acidic oxide... View Article

A metal carbonate X on reacting with acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at the anode during electrolysis of brine is passed on dry Y, and it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z.

Answer: Here, X is calcium carbonate (CaCO3) Y is slaked lime Z is bleaching powder (CaOCl2) G is chlorine gas X... View Article

For making a cake, baking powder is taken. If at home, your mother uses baking soda instead of baking powder in cake, (a) how will it affect the taste of the cake and why? (b) how can baking soda be converted into baking powder? (c) what is the role of tartaric acid added to baking soda?

Answer: (a) If we use baking soda instead of baking powder taste of the cake will be bitter. Upon heating baking, soda sodium carbonate will be... View Article

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