SSC GD Constable GK Questions 2026

An amphoteric oxide reacts with both acids and bases to form salts, and aluminium oxide does exactly that, behaving as a base towards hydrochloric acid and as an acid towards sodium hydroxide; zinc oxide is the other amphoteric oxide asked in examinations.

In galvanisation iron or steel is given a coating of zinc, usually by dipping it in the molten metal, and the coating protects the iron in two ways: it keeps out air and moisture, and because zinc is more reactive than iron it corrodes in place of the iron even…

Galena is lead sulphide, the principal ore from which lead is obtained; being a sulphide it is concentrated by froth flotation and then roasted in air to the oxide before reduction.

Silver has the highest electrical conductivity of all metals and also the highest thermal conductivity, but it is costly and tarnishes, so it is used only in specialised contacts and instruments.

Aqua regia is three parts concentrated hydrochloric acid to one part concentrated nitric acid, and the name means royal water, given because the mixture attacks the noble metals gold and platinum, which neither acid can dissolve on its own.

Mercury is the only metal that is liquid at ordinary room temperature, which is why it was long used in thermometers and barometers; it is also the metal that forms amalgams, alloys in which mercury is one component.

Brass takes the workability of copper and the hardness of zinc, resists corrosion and is easy to cast, which is why it is used for utensils, locks, taps, fittings and wind instruments.

Ductility is the property of being drawn into a wire, and gold is the most ductile metal known; it is also the most malleable, so a very small quantity can be beaten into an extremely thin sheet or drawn into a very long wire.

Silver is an element, a pure metal with its own place in the periodic table, so it cannot be an alloy; an alloy is a homogeneous mixture of two or more metals, or of a metal with a non-metal such as carbon.

Calamine is zinc carbonate, and since it is a carbonate ore it is converted to the oxide by calcination, that is by heating in the absence of air, before being reduced to the metal.

Under Article 360(4), while a Financial Emergency is in operation, the President can issue directions for reducing the salaries and allowances of all or any class of persons serving the Union, including the judges of the Supreme Court and the High Courts.

Article 360 has never been used. Even in 1991, when India faced a severe balance of payments crisis, had foreign exchange reserves for only a few weeks of imports and had to pledge gold to raise loans, the government chose economic reforms rather than a Financial Emergency.

It allows the President to proclaim a Financial Emergency if satisfied that the financial stability or credit of India, or of any part of its territory, is threatened.

The Government of India set up the Sarkaria Commission in June 1983, under Justice R.S. Sarkaria, a retired judge of the Supreme Court, to review the working of Centre-State relations.

Once approved by Parliament, President's Rule lasts six months and can be extended by fresh approval for six months at a time, but never beyond three years in all.

Under Article 356, if the President is satisfied, on the Governor's report or otherwise, that the government of a State cannot be carried on in accordance with the Constitution, he or she can take over the functions of the State government, which in practice means dismissing the State's Council of…

On the night of 25 June 1975, President Fakhruddin Ali Ahmed proclaimed a National Emergency on the ground of "internal disturbance", on the advice of Prime Minister Indira Gandhi.

A National Emergency under Article 352 has been proclaimed three times: in October 1962, when China attacked India; in December 1971, during the war with Pakistan that led to the creation of Bangladesh; and in June 1975, on the ground of "internal disturbance", during Indira Gandhi's government.

India's first National Emergency was proclaimed on 26 October 1962, during the war with China, on the ground of external aggression.

While a Proclamation of National Emergency is in operation, Parliament can by law extend the normal five-year term of a State Legislative Assembly (Article 172) and of the Lok Sabha (Article 83) by up to one year at a time.