SSC GD Constable GK Questions 2026

The alkene series begins at two carbon atoms, so its first member is ethene, C2H4, and its second member is propene, C3H6.

C3H4 is propyne, and it fits the alkyne general formula CnH2n-2 when n equals 3. Alkynes are unsaturated hydrocarbons that carry at least one carbon-to-carbon triple bond, and the first member of the family is ethyne, C2H2, better known as acetylene and burnt with oxygen in welding torches.

Put n equal to 3 in the alkyne general formula CnH2n-2 and the result is C3H4, which is propyne, the second member of the alkyne series.

An alkene is an unsaturated hydrocarbon in which two carbon atoms are joined by a double bond, so the carbon-to-carbon double bond is its identity.

Alkanes are saturated hydrocarbons, so every bond between two carbon atoms is a single bond and all the remaining valencies are filled by hydrogen.

The halogens are placed in Group 17 of the modern periodic table. This family has five members - fluorine, chlorine, bromine, iodine and astatine.

An alkene carries one carbon-to-carbon double bond, and that bond uses up two hydrogen atoms that a saturated chain would have held, so the formula drops from CnH2n+2 to CnH2n. Putting n equal to 2 gives C2H4, ethene, the simplest alkene; n equal to 3 gives C3H6, propene.

Alkanes are saturated hydrocarbons in which carbon atoms are joined only by single bonds, and such a chain carries the largest possible number of hydrogen atoms, given by CnH2n+2.

Carbon is a non-metal, so it does not show metallic character; it neither loses electrons to form positive ions nor shows the lustre and malleability of metals.

An ionic compound is a lattice of positive and negative ions held by strong electrostatic attraction, and that force explains all its other properties.

A covalent bond is formed when two atoms share one or more pairs of electrons so that each completes its outermost shell.

A metal loses electrons and a non-metal gains them, so the transfer makes oppositely charged ions that attract each other, and that attraction is an ionic bond.

Sodium is a metal that gives up an electron easily and chlorine is a non-metal that accepts one, so the two form sodium chloride, an ionic compound.

Ionic compounds dissolve well in water but not in kerosene, petrol or other non-polar organic solvents, so this statement is not a property of theirs.

The element with atomic number 56 is barium, and its outermost electron enters the 6s orbital, so it sits in the s-block.

Relative atomic mass is measured against the carbon-12 atom, one-twelfth of whose mass is taken as the standard unit. That unit is the atomic mass unit, written u, and it is defined as exactly one-twelfth of the mass of one atom of carbon-12.

Melting of ice only changes the state of water from solid to liquid; no new substance is formed, so it is a physical change.

Ice melts at 0 degrees Celsius, and 0 degrees Celsius is 273 K on the Kelvin scale. To change Celsius into Kelvin, add 273 to the Celsius reading, so 0 + 273 gives 273 K; the melting point of ice is usually written as 273.15 K in exact work.

The balanced equation is 2FeSO4 → Fe2O3 + SO2 + SO3, so p = 2, q = 1, r = 1 and s = 1.

In the given equation sodium hydroxide, which is a base, reacts with sulphuric acid to give sodium sulphate and water, and a reaction in which an acid and a base cancel each other to form a salt and water is called neutralisation.