Test: Periodic Trends in Properties of Elements - Chemistry MCQ

Atomic radii decreases along the periods because as the number of electrons increases in the same shell of the atom, the effective nuclear attraction increases, thereby reducing the distance between the outer shell and the nucleus i.e. decreasing atomic radii.

The minimum amount of energy that is required to remove an electron from an atom is called Ionization enthalpy. It is expressed in the units KJ/mol. Electron affinity is the change in the energy when we add an electron to a neutral atom. Electropositivity is a metallic characteristic. A catalyst speeds up the reaction.

As the ionization energy is the minimum amount of energy that is required to remove an electron from an atom. As the energy is always needed for the removal of an electron from an atom, the values of ionization energies are always positive.

The Elements Li and Mg, Be and Al are similar to each other in the case of formation of different compounds in a similar composition. They have a sort of similar behaviour with each other, so they are said to be in a diagonal relationship as per their place in the periodic table.

In the superoxide of the element, the oxygen’s oxidation state is given by -1/2. In peroxides, the oxidation state of oxygen is -1 as in case of hydrogen peroxide. The oxygen’s oxidation state in KO₂ is -1/2.

O^2-, F^–, Na⁺ and Mg²⁺ are known as isoelectronic species as they all have the same no. of electrons(10). Isotopes contain the same no. of protons but a different number of neutrons. Isobars have the same mass number but a different atomic number.

Electronegativity is the measure of the ability to attract shared electrons to itself of an atom in a chemical compound. The values of electronegativities of Li, Na, K, Rb and Cs are 1, 0.9, 0.8, 0.8 and 0.7 respectively.

The total charge of the compound KMnO4 is zero as it is a neutral and stable compound. As we know the oxidation states of K and O are +1 and -2 respectively. So +1 + Mn charge + 4(-2) = 0; Mn charge = 7.

N₂O is called laughing gas as it has euphoric effects after being inhaled. It is one of the World Health Organization’s Essential Medicines. it is used for recreational and anaesthetic purposes mostly.

A litmus paper is a dye that is extracted from lichens. It used to test acidic nature and basic nature of a substance. Red colour indicates acidic nature and blue colour indicated basic nature. Neutral litmus paper is purple in colour.