Give reasons (a) Platinum, gold and silver are used to make jewellery. (b) Sodium, potassium and lithium are stored under oil. (c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. (d) Carbonate and sulphide ores are usually ...Read more
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Dead remains of two species A and B were buried. Later only A’s body was found to be a fossil but not B’s give reason.
Differentiate between metal and non-metal on the basis of their chemical properties.
Why are some substances biodegradable and some non-biodegradable?
Translate the following statements into chemical equations and then balance them. (a) Hydrogen gas combines with nitrogen to form ammonia. (b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide. (c) Barium chloride reacts with aluminium sulphate ...Read more
With the help of an example explain how genes control characteristics or trait.
Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
Male has 23 pairs of chromosomes and female has 23 pairs of chromosomes. Then why doesn’t an offspring have 46 pairs of chromosomes which is obtained by the fusion of these two eggs.
Give any two ways in which biodegradable substances would affect the environment.
Balance the following chemical equations. (a) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O (b) NaOH + H2SO4 → Na2SO4 + H2O (c) NaCl + AgNO3 → AgCl + NaNO3 (d) BaCl2 + H2SO4 → BaSO4 + HCl