(i) Lattice energy of BeO is comparatively higher than the hydration energy. Therefore, it is almost insoluble in water. Whereas BeSO₄ is ionic in nature and its hydration energy dominates the lattice energy.
(ii) Both BaO and BaSO₄ are ionic compounds but the hydration energy of BaO is higher than the lattice energy, therefore it is soluble in water.
(iii) Since the size of Li⁺ ion is very small in comparison to K⁺ ion, it polarises the electron cloud of I^- ion to a great extent. Thus LiI dissolves in ethanol more easily than the KI.

Charles' law states that for a fixed mass of a gas at constant pressure, the volume is directly proportional to temperature (K).
\(V\propto T\) (or)  = \(\frac{V}{T}\) Constant

Volume vs Temperature:
If a balloon is moved from an ice water bath to a boiling water bath, the gas molecules inside move faster due to increased temperature and hence the volume increases.

P_Ne = X_Ne P_Total
\(X_{Ne}=\frac{n_{Ne}}{n_{Ne}+n_{Ar}+n_{Xe}}\)
\(=\frac{4.76}{4.76+0.74+2.5}=0.595\)
\(X_{Ar}=\frac{n_{Ar}}{n_{Ne}+n_{Ar}+n_{Xe}}\)
 \(=\frac{0.74}{4.76+0.74+2.5}=0.0093\)
\(X_{Xe}=\frac{n_{Xe}}{n_{Ne}+n_{Ar}+n_{Xe}}\)
\(=\frac{2.5}{4.76+0.74+2.5}=0.312\)
P_Ne = X_Ne P_Total = 0.595 x 2
= 1.19 atm.
P_Ar = X_Ar P_Total = 0.093 x 2
= 0.186 atm.
P_Xe = X_Xe P_Total = 0.312 x 2
= 0.624 atm.

In a reaction involving the collection of gas by downward displacement of water, the pressure of dry vapor collected can be calculated using Dalton's law.
P_{dry gas collected} = P_Total - P_{water vapour}
P_{water vapour} is generally referred as aqueous tension and its values are available for air at various temperatures. These values are relevant in weather forecast.

(i) Boyle's point is the temperature at which, real gases behave ideally over a range of low pressures.
(ii) The Boyle point varies with the nature of the gas.
(iii) Above the Boyle point, Z > 1 for real gases. i.e., they show positive deviation.
(iv) Below the Boyle point, the real gases first show a decrease for Z, reaches a minimum and then increase with increase in pressure.

Given, P₁ = 10 atm; P₂ = ?; T₁ = 300K; T₂ = 373
\(\frac{P_1}{T_1}=\frac{P_2}{T_2}\)
P2 = T2 = 373
\(\frac{100}{300}=\frac{P_2}{373}\)
= 124.3 atm

(i) They assume the volume and shape of their container
(ii) They are the most compressible state of matter
(iii) They mix thoroughly when confined to the same container
(iv) They have much lower densities than liquids and solids
(v) Their pressure is uniform on all sides of the. container.

(i) 2Li + 2H₂O ⟶ 2LiOH + H₂
                             (Lithium hydroxide)
(ii) 2Na + 2C₂H₅OH ⟶ 2C₂H₅ONa + H₂
                                        (sodium ethoxide)
(iii) \(CH\equiv CH\overset { Na }{ \rightarrow } HC\equiv CNa\overset { Na }{ \rightarrow } \underset { (sodium\quad acetylide) }{ NaC } \equiv C-Na\).

BaCO₃ is thermally the most stable.
Thermal stability increases with Increase In cationic size.
The increasing order of size of cation of the alkaline earth metals is Mg < Ca < Sr < Ba.
Hence the increasing order of thermal stability of the given alkaline earth metal carbonates is
MgCO₃ < CaCO₃ < SrCO₃ < BaCO3

(I) ⁹⁰Sr is used in cancer therapy.
(ii) ⁸⁷Sr / ⁸⁶Sr ratios are commonly used in marine investigations as well as in teeth, tracking animal migrations or in criminal forensics. 
(iii) Dating of rocks.
(iv) As a radioactive tracer in determining the source of ancient archaeological materials such as timbers and coins.

Reasons for anomalous behaviour of lithium,
(i) Extremely small in size
(ii) Greater polarizing power of ion
(iii) Least electropositive character
(iv) Non-availability of d-orbitals

Alkali metals have one e^o in their outer most shell. Alkaline earth metals have 2 e^o in their outer most shell. More valence electrons and more positively charged nucleii leads to greater opportunity for metallic bonding.

In Na₂ SO₄.10 H₂O. So the metal will be Na (sodium). The salt is washing soda.

It will be more difficult to drink water with a straw on the top of a Mount Everest. This is because the reduced atmospheric pressure is less effective in pushing water up into the straw, below the water surface.
The force that propels water through a straw is atmospheric pressure, which is less at high altitude.

The passenger in a moving bus falls in the forward direction, when brakes are applied suddenly is in accordance with Newton's first law of motion.
When breaks are applied, the automobile comes to rest but the passenger due to inertia of motion tend to continue to move in forward direction hence fall forward.
The movement of helium balloon in the opposite direction is due to the difference in the density of surrounding air. When the car stops suddenly, the air moves forward due to inertia of motion.
As a result the air in the front of the car is more dense that at the rear of the car creating more pressure on the front side of the balloon. This causes the balloon move towards the rear of the car where air is less dense.
The body is at rest but the car is forward motion, due to inertia the passengers are pushed toward the front of the car on forward acceleration.

a) Hydrogen is the lightest gas in the atmosphere. So it rises up and other gases which are heavier like O₂ & N₂ come down towards the surface of the earth according to Graham's law of diffusions \(\mathrm{r} \alpha \sqrt{\frac{1}{M}}\). Hydrogen diffuses very fast. Its mean speed in greater than the escape velocity from the earth. As a consequence, H₂ would have escaped from the atmosphere long time ago.
b) The acceleration due to gravity 'g' on moon surface is small. The value of escape velocity is also small. The molecules of the atmospheric gases on the moon's surface have thermal velocities greater than the escape velocity.
All the molecules have escaped. So the atmosphere is so thin.

Gases which obey Boyle's Law and Charle's law or ideal gas equation PV = nRT are called ideal gases.
All gases whose behaviour is consistent with the assumption of kinetic theory of gases under all condition are called ideal gases.

2NH₃ + H₂O + CO₂ ⟶ (NH₄)₂ CO₃
(NH₄)₂ CO₃ + H₂O + CO₂ ⟶ 2NH₄ HCO₃
2NH₄HCO₃ + NaCl ⟶ NH₄Cl + NaHCO₃
2NaH CO₃ ⟶ Na₂ CO₃ + CO₂ + H₂O.

The solubility product of NaCl is lower than that of NaOH. The more soluble a substance is, the higher the K_sp value it has In aqueous solution NaOH gives OH^- ions. It can be solvated by establishing H-bonds with water molecules. So it is more water soluble.

Magnesium oxide in having higher melting point. The lattice energy of MgO & MgF₂ are 3938 and 2957 respectively.
MgO has +2, -2 charges, MgF₂ has +2, -1 charges. When the two charges are multiplied together, MgO results in larger amount of lattice energy since it has a higher charge, The strong attraction cause most ionic material to be hard and brittle and have high melting points.