Question Library

H2SO4 (O.N of hydrogen * 2 ) + O.N of sulphur + O.N of oxygen * 4 = 0 ∴ 1 * 2 + 6 + 4x = 0 2 + 6 + 4x = 0 8 + 4x = 0 4x 0 - 8 = -8 4x = -8 x = -8/4 = -2

MnO\(_2\)(s) + xHCl(aq) → MnCl\(_2\)(aq) + yH\(_2\)O(l) + zCl\(_2\)(g) First, balance the chemical equation, then equate each of the letters with the coefficients. On balancing, we have : MnO\(_2\)(s) + 4HCl(aq) → MnCl\(_2\)(aq) + 2H\(_2\)O(l) + Cl\(_2\)(g) Therefore, x = 4,y = 2 and z = 1

2 * 35.5g of chlorine has a volume of 22.4 dm3 at s.t.p ∴ xg of chlorine will have a volume of 1.12 dm3 x = (1.12 * 35.5 * 2)/22.4 = 3.55g

In 1909, Robert Millikan and Harvey Fletcher conducted the oil drop experiment to determine the charge of an electron.

CH\(_4\)(g) + 2O\(_2\)(g) → 2H\(_2\)O(g) + CO\(_2\)(g) First, ensure the chemical equation is balanced, stoichiometrically. i.e CH\(_4\) reacts with 2O\(_2\) in ratio 1 : 2 If 1 mole of CH\(_4\) reacts with 2 moles of O\(_2\) Then 45 cm\(^3\) CH\(_4\) react with X cm\(^3\) O\(_2\) i.e 1cm\(^3\) = 2cm\(^3\) 45cm\(^3\)= X cm\(^3\) X = 45 x 2 = 90 cm\(^3\)

N.B : Atomic number = no. of protons = no. of electrons = 15 Orbital configuration of the neutral atom of the element = 2, 8, 5 which represents the shells starting from the first which is K, L, M respectively. i.e K = 2, L = 8 , M = 5. Therefore, the L - shell has 8 electrons.

When the electrons are drawn out in the orbitals, following the Hund's rule, the diagram above is what will be obtained.

When a gas is compressed to half its volume, the average intermolecular distance decreases because the same number of gas molecules are now confined to a smaller space, forcing them closer together, resulting in a smaller average distance between each molecule. Conversely, when the volume of a gas is reduced, the frequency of collisions between molecules increases; this is because the molecules have less space to move around, leading to more frequent interactions with each other and the container walls.

If the metal X forms two bromides with the formulae XBr\(_2\) and XBr\(_3\), it simply means it has variable oxidation number or states which is one of the characteristics of transition metals. This implies X is a metal. However, whenever a metal combines with a non-metal, there is usually a transfer of electrons from the metals to the non-metals, and the type of bond formed is the ionic or electrovalent bond.

Petrol and water are immiscible liquids, so the best method of separation of petrol and water is by a separating funnel.

Aromatic compounds are chemical compounds that consist of conjugated planar ring systems accompanied by delocalized pi-electron clouds in place of individual alternating double and single bonds. In a simpler term, aromatic compounds are compounds of Benzene and its derivatives.e.g Benzene, Phenol, Toluene, xylene, anthracene, Naphthalene etc all cyclically conjugated. The compound in option A is called phenol - a benzene ring with an hydroxyl group (OH) attached to C-1.

A nucleophile is considered an electron donating species, meaning it readily donates an electron pair to form a bond with another molecule, typically an electrophile, in a chemical reaction; essentially acting as a Lewis base. CN\(^-\) (cyanide ion) is considered a nucleophile. This is because it has a negative charge and a lone pair of electrons that it can donate to form a bond with a positively charged species, making it an electron-rich species characteristic of nucleophile. Conversely, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids.

An "anti-knock agent" for petrol (or gasoline) is a chemical additive that is added to fuel to prevent engine knocking, which is a knocking sound produced by premature ignition in the combustion chamber, and essentially increases the fuel's octane rating by delaying ignition. Option A - 2,3- dimethylpentane Option B - 3-methylhexane Option C - 3-methylhexane Option D - 2,2-dimethylpentane Both 2,3-dimethylpentane and 2,2-dimethylpentane are branched-chain structures. However, 2,2-dimethylpentane has a more compact, highly branched structure, which is generally associated with higher octane ratings and better anti-knock properties. In contrast, 2,3-dimethylpentane has a slightly less branched structure, which may result in slightly lower octane ratings. So, while both compounds are branched, the degree of branching and the resulting octane rating can differ.

Styrene is produced from the monomer ethylbenzene through a process called dehydrogenation, where hydrogen is removed from ethylbenzene to create styrene; dehydrogenation of ethylbenzene, a compound obtained by reacting ethylene and benzene. However, ethylene is also known as ethene.

The structural isomers of chlorobutane are: 1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, and 2-chloro-2-methylpropane; in total, there are four structural isomers of chlorobutane. Explanation: 1-chlorobutane: Chlorine is attached to the first carbon of a straight carbon chain. 2-chlorobutane: Chlorine is attached to the second carbon of a straight carbon chain. 1-chloro-2-methylpropane: A methyl group is attached to the second carbon of a propane chain, with chlorine on the first carbon. 2-chloro-2-methylpropane: Chlorine is attached to a carbon that is also connected to two methyl groups.