Chemistry

(a) The element V has the highest first ionization enthalpy (? _iH₁) and positive electron gain enthalpy (? _egH) and hence it is the least reactive element. Since inert  gases have positive? _egH, therefore, the element-V must be an inert gas. The values of? _iH₁,  ? _iH₂ and? _egH match that of He.

(b) The element II which has the least first ionization enthalpy (? _iH₁) and a low negative electron gain enthalpy (? _egH) is the most reactive metal. The values of ? _iH₁,  ? _iH₂ and? _egH match that of K (potassium).
               

(c) The element III which has high first ionization enthalpy (? _iH₁) and a very high negative electron gain enthalpy (? _egH) is the most reactive non-metal. The values of? _iH₁,  ? _iH₂ and? _egH match that of F (fluorine).
               

(d) The element IV has a high negative electron gain enthalpy (? _egH) but not so high first ionization enthalpy (? _egH). Therefore, it is the least reactive non-metal. The values of? _iH₁,  ? _iH₂ and? _egH match that of I (Iodine).
               

(e) The element VI has low first ionization enthalpy (? _iH₁) but higher than that of alkali metals. Therefore, it appears that the element is an alkaline earth metal and hence will form binary halide of the formula MX₂ (where X = halogen). The values of? _i H₁,  ? _iH₂ and? _egH match that of Mg (magnesium).
               

(f) The element I has low first ionization (? _iH₁) but a very high second ionization enthalpy (? _iH₂), therefore, it must be an alkali metal. Since the metal forms a predominantly stable covalent halide of the formula MX (X = halogen), therefore, the alkali metal must be least reactive. The values of? _iH₁,  ? _iH₂ and? _egH match that of Li (lithium).

This is a long answer type question as classified in NCERT Exemplar

Enzyme inhibitors block the binding site of enzyme and prevent the binding of substrate and then inhibit the catalytic activity of enzyme. They act in two different ways.

(i) Drugs which compete with substrate for their attachment on the active sites of enzymes are called competitive inhibitor.

(ii) Some drugs bind to a different site of enzyme called allosteric site. It changes the shape of the active site and substrate cannot recognize it. Such enzymes are called non-competitive inhibitor the bond formed between enzyme and an inhibitor is strong covalent bond then enzyme is blocked permanently.

This is a long answer type question as classified in NCERT Exemplar

Synthetic detergents are cleansing agents which have all the properties of soaps, but which actually do not contain any soap. These can be used both in soft and hard water as they given foam even in hard water. Detergents can be classified into three groups according their chemical nature.

(i) Anionic detergents – These are sodium salts of sulphonated long chain alcohols or hydrocarbons and sodium alkyl benzene sulphonates. e.g., CH₃ (CH₂)₁₀CH₂OSO₃^– Na⁺
Anionic part of these detergents is involved in cleansing action.

(ii) Cationic detergents – These are quaternary ammonium salts of amines with acetates, chlorides or bromides as anions.

(iii) Non-ionic detergents – These do not contain any ion in their constitution, e.g., detergent formed by steric acid and polyethylene glycol. CH₃ (CH₂)₁₆C00 (CH₂CH₂0)_nCH₂CH₂OH.

 

Pollution by synthetic detergents can be minimized by reducing the branching of hydrocarbon chain or using unbranched hydrocarbons.

This is a long answer type question as classified in NCERT Exemplar

Enzymes catalyse many reactions by

(i) Holding the substrate for a chemical reaction. Active sites hold the substrate molecule in a suitable positions So that it can be attacked by the reagent effectively. Substrates bind to the active site of enzyme through ionic or hydrogen bonding or van there Waals or dipole-dipole, interactions.

(ii) Enzyme provides functional groups that will attack the substrate to carry out the chemical reaction. This function is carried out chemical reaction: This function iscarried out by some other amino acid residues of protein present on the active site of the enzyme. These free amino group to attack the substrate and bring about chemical reaction. Drugs can inhibit these activities by blocking site of enzyme and prevent the binding of substrate. Such drugs are called enzyme inhibitors.