Full Mock Test (40 Questions)

Explanation:

Sublimation is the direct change of a substance from solid to vapour without passing through the liquid state.

For iodine crystals to sublime, the particles must gain enough energy to overcome the intermolecular forces holding them in the solid lattice.

Once these forces are overcome, the particles escape directly into the gaseous state.

Therefore, the particles must acquire energy greater than the forces of attraction in the solid.

Solution:

relative molecular weight of SO₂ = S + ([O2])

Given:

• S = 32
• O = 16

SO₂ = 32 + 2(16) = 32 + 32

SO₂ = 64

Relative percentage of sulphur = \(\Large \frac{32}{64}\times \frac{100}{1}\normalsize = 50\%\)

Since sulphur = 32

% of sulphur = 50%

Solution:

Number of atom = number of mole × Avogadro’s constant

Number of moles = \(\Large\frac{mass}{molar\;mass}\)

= \(\Large\frac{6}{24} = \normalsize 0.25mol\)

Number of atom = 0.25 × 6.02 × 10²³

= 1.51 × 10²³

Explanation:  Z = 1s²2s²3p⁶3s²3p¹

We have Z³⁺  and \(\normalsize SO_4^{-2}\)

The reaction is: \(\normalsize Z^{3} \: + \: SO^{2-}_4 \rightarrow Z_{2}\left ( SO_{4} \right )_{3}\)

= Z₂(SO₄)₃

Explanation:

Using the combined gas law,

⇒ \(\Large \frac{P_1V_1}{T_1} =\frac{P_2V_2}{T_2}\).

If P₂ = 2P₁ and V₂ = 2V₁,

then \(\normalsize T_2 = \Large \frac{(2P_1)(2V_1)T_1}{P_1V_1} \\ = \normalsize 4T_1 \\ =\normalsize 4 \times 273 = 1092 \: K\)

Explanation: Plotting solubility curves of different substances on the same axes allows for a visual comparison of their solubility behavior at various temperatures, showing which substance is more soluble at a given temperature.

Explanation: Collisions between gas molecules are perfectly elastic, not inelastic. This means that there is no loss of kinetic energy during the collisions

Explanation:

Solutbility = \(\Large \frac{Mass}{Molar\:mass} \: \times \: \frac{1000}{Volume}\)

Molar mass KNO₃ = 39 + 14 + 3(16) = 101 g/mol.

Solubility (mol/dm³) = \(\Large \frac{g}{g/mole} \: \times \: \frac{1000 \: cm^3}{cm^3}\)

= \(\Large \frac{20.2}{101} \: \times \: \frac{1000}{100} \\ = \normalsize 2.00 \: mol/dm^3\)

Explanation:

X-rays are used to study the arrangement of particles (atoms, molecules) within a crystal lattice through a technique called X-ray crystallography, by measuring the angles and intensities of scattered X-rays.

This technique exploits the fact that X-rays have wavelengths comparable to the spacing between atoms in a crystal. When a beam of X-rays interacts with a crystal, the regular arrangement of atoms causes the X-rays to diffract (scatter) in specific directions.

Explanation:

Going across the period, electrons are added to the same outer shell with a corresponding increase in the number of the positively charged protons in the nucleus, which produces an increased effective nuclear charge. The increased nuclear charge means a stronger pull exerted by the nucleus on the electrons of the outer shell, hence the contraction of the atoms, moving across the period.

Explanation:

The electronic configuration 1s² 2s² 2p⁶ 3s² 3p³ corresponds to atomic number 15, which is phosphorus.

Phosphorus has five valence electrons and commonly exhibits valencies of 3 and 5.

Therefore, when phosphorus reacts with a halogen Y, it can form the halides EY₃ and EY₅.

Explanation: The bond between magnesium and chlorine in magnesium chloride (MgCl₂) is ionic (electrovalent), formed through the transfer of electrons from magnesium to chlorine atoms.

Solution:

Equation: ⇒ \(\normalsize Ca(HCO_3)_2\rightarrow CaCO_3\;{precipiate}+H_2O+CO_2\)

{in the presence of heat}.

Volume = 200 cm³ to dm³ = \(\Large\frac{200}{1000} =\normalsize 0.2\: dm^{3}\)

⇒ \(\normalsize C =\Large\frac{0.5\:mol}{dm^{3}}=\normalsize 0.5\: M\)

Number of moles = CV

= 0.5 × 0.2

= 0.1 mole

From the above equation:

1 mole of Ca(HCO₃)₂  gives 100 g of CaCO₃

0.1 mole of Ca(HCO₃)₂ will give x g of CaCO₃

⇒ \(\Large \frac{1}{0.10} = \frac{100}{x}\)

⇒ \(\normalsize x =\Large\frac{0.1\times 100}{1}\)

= 10 g

Explanation:

Temporary hardness is the hardness of water which can be removed or softened by boiling. Temporary hardness is caused by hydrogen trioxocarbonate (IV) of calcium or magnesium, i.e. Ca(HCO₃)₂ or Mg(HCO₃)₂.

Explanation: Helium is a noble gas (chemically inert), non‑combustible, and less dense than air, so it provides lift safely.

Explanation: The pink colour of phenolphthalein in an alkaline medium is because it is a weak acid which can lose H⁺ ions in solution. The phenolphthalein molecule is colourless, and the ion is pink.

Explanation:

At the cathode:

Zn²⁺ + 2e^- → Zn(s)

2F (i.e. 2 × 96500 C) deposits 65 g of Zn.

So, charge needed to deposit 3.25 g of Zn is:

⇒ \(\normalsize Q = \Large \frac{3.25 \times 2 \times 96500}{65} \\ = \normalsize 9650\ \text{C}\)

Time = 2 hours = 2 × 60 × 60 = 7200 s

Using Q = It:

⇒ \(\normalsize I= \Large \frac{Q}{t} \\ = \Large\frac{9650}{7200} \\ = \nromalsize 1.34\ \text{A}\)

Solution

Al³⁺_(aq)  + 3e^-   →  Al_(s)

3F                          27g

3F   =   ( 3 × 96500) C   =   289500 C

Q    =  It   =   (10 × 1930) C    =  19300 C

From the  reaction,

289500 C  =       27g   of Al

19300 C  =  \(\Large \frac {19300 \: \times \: 27} {289500}\)

= 1.8 g

Explanation:

HClO₄ = 0

+1 + Cl + (-2 × 4) = 0

+1 + Cl – 8 = 0

Cl = 8 - 1

Cl = +7

Explanation: Br₂ is the oxidizing agent, and H₂S is the reducing agent. Oxidation is the loss of electrons, gain of oxygen, or loss of hydrogen.

Explanation:

Efflorescence is the process where a hydrated salt loses its water of crystallization when exposed to the air, often resulting in a powdery appearance.

Examples of Efflorescent salts are:

• Na₂CO₃  .  10H₂O
• Na₂SO₄  . 10H₂O

Explanation:

The reaction produces more moles of gas (2 mol on the left, 4 mol on the right). So decreasing pressure favours the side with more gas molecules (products).

Since ΔH is positive (endothermic), increasing temperature favours the forward reaction. Therefore, increase temperature and decrease pressure will favour the yield of products.

Explanation:

Activation energy is the minimum energy required for a reaction to occur.
On an energy profile diagram, it is the vertical distance between the energy of the reactants and the peak of the curve.

From the diagram:
– Energy of reactants ≈ 100 kJ
– Peak of catalyzed curve ≈ 200 kJ

Therefore,
Activation energy (catalyzed reaction) = 200 − 100 = 100 kJ

A catalyst lowers the activation energy of a reaction by providing an alternative pathway with lower energy. Hence, the activation energy of the catalyzed reaction is 100 kJ.

Explanation:

The reaction is endothermic, so ΔH > 0. Also, the number of gas molecules decreases from 4 moles (reactants) to 2 moles (products), so ΔS < 0.

Therefore, ΔG = ΔH - TΔS becomes: (+) − T(−) = (+) + (+),

so ΔG is positive at room temperature (and in fact at all temperatures).

Explanation: Exposing chlorine water to sunlight causes it to decompose to HCl gas and oxygen. When chlorine water is exposed to strong sunlight, it produces an odourless and colourless gas called oxygen.

Explanation:

Constituents of Duralumin are: Al, Cu, Mg, and Mn.

Constituents of Alnico are: Al, Ni, and Co.

Explanation: Chlorofluorocarbons (CFCs) are a major contributor to the depletion of the ozone layer, as they release chlorine atoms into the stratosphere that react with and destroy ozone molecules.

Explanation: Transition metal ions with partially filled d orbitals exhibit characteristic properties like forming colored compounds and acting as catalysts due to the ease with which electrons can be removed or added to these orbitals.

Explanation:

NaNO₃ + H₂SO₄ → NAHSO₄ + HNO₃

Explanation:

Magnetic separation: This method involves passing magnetic ores, e.g. copper ore, through a magnetic separator.

The ore is finely crushed and passed over the magnetic roller, where one is magnetic, and the other is nonmagnetic. Ores with a high metal content will attract and attach to the magnetic roller and get deflected into a pile, and the non-magnetic gangue particles will repel and fall into the pile from the conveyor belt.

Explanation:

Alumina, dissolved in molten cryolite, is electrolyzed to obtain pure aluminium.

Explanation:

Water gas, a mixture of hydrogen and carbon(II) oxide is prepared by passing steam over red hot coke. Water gas is a gaseous fuel produced from coke.

Explanation: Allotropy is the existence of an element in more than one form in the same physical state (e.g., rhombic and monoclinic sulphur).

Explanation: The suitable drying agent for ammonia (NH₃) is calcium oxide (CaO), also known as quicklime.

Explanation: The parent chain is ethane (2 carbons). Number the chain to give the lowest set of locants: placing the CF₃ group at carbon 1 gives 1,1,1-trifluoro and both halogens (Br and Cl) at carbon 2. Substituents are listed alphabetically, so bromo comes before chloro. Therefore the name is 2-bromo-2-chloro-1,1,1-trifluoroethane.

Explanation: Benzene is prepared from ethyne by the process of cyclic polymerization. In this process, ethyne is passed through a red-hot iron tube at 873 K. The ethyne molecules then undergo cyclic polymerization to form benzene.

Explanation:

Hydrolysis of starch yields 2 molecules of glucose.

While the hydrolysis of starch primarily yields glucose, fructose can be produced from starch through enzymatic isomerization of glucose, which is a subsequent step in the process of creating high-fructose syrups.

Explanation:

An unsaturated hydrocarbon contains at least one carbon–carbon double or triple bond.

Propene (C₃H₆) contains a carbon–carbon double bond and is therefore unsaturated.

Alkanes such as pentane contain only single bonds and are saturated.

Explanation: Both butane and 2-methylpropane are members of the same homologous series, specifically the alkane series (C_nH_{2n + 2}), and they are structural isomers with the same molecular formula (C₄H₁₀) but different structural arrangements.

Explanation: Toluene is found naturally in crude oil and is used in oil refining and the manufacturing of paints, lacquers, explosives (TNT) and glues.