On heating incineration might take place due to the increase of pressure

Calcium Sulphate (plaster of paris), CaSO₄. 1/2H₂O :
It is a hemihydrate of calcium sulphate. It is obtained when gypsum, CaSO₄ .2H₂O,is heated to 393 K
2(CaSO₄.2H₂O) ⟶ 2CaSO₄,H₂O + 3H₂O
Above 393 K, no water of crystallisation is left and anhydrous calcium sulphate, CaSO₄ is formed. This is a known 'dead burnt plaster'.
It has a remarkable property of setting with water. on mixing with an adequate quantity of water it forms a plastic mass that gets into hard solid in 5 to 15 minutes.

This is due to the smaller size and relatively high charge as Be²⁺ ion. Moreover Beryllium is a non - metal. But Magnesium is a metal. In the case of beryllium the ionisation energy and electronegativity of the halides are almost similar; but there is a vast difference in IE and electronegativity between Mg and halides.

The largest use of plaster of paris is in the building industry as well as plasters. It is used for immobilising the affected part of organ where there is a bone fracture or sprain. It is also employed in dentistry, in ornamental work and for making casts of statues and busts.

If there is a tiny sticky area on the walls of the container of a gas, then the collision of the molecules will not be elastic. So the gas will behave as a real gas. So the pressure will be less than the calculated value.

(i) Gypsum is usually white, colourless or grey in colour.
(ii) It can also be found in the shades of pink, yellow, brown and light green, mainly due to the presence of impurities.
(iii) Gypsum crystals are found to occur in a form that resembles the petals of a flower. This type of formation is referred to as 'desert rose', as they mostly occur in arid areas or desert terrains

Only below the critical temperature, by the application of pressure, a gas can be liquefied. CO₂ has critical temperature as 303.98 K. Room temperature means (30 + 273 K) 303 K. At room temperature, (critical temperature) even by applying large amount of pressure CO₂ cannot be liquefied. Only below the critical temperature, it can be liquefied. At room temperature, CO₂ remains as gas.

Barium peroxide is prepared by heating monoxides with oxygen at high temperature.
\(\underset{Barium\ oxide}{2BaO}+O_2\xrightarrow{Δ}\underset{Barium\ peroxide}{2BaO_2}\)

The decrease in ionization enthalpy down the group permits easy availability of electrons to forms H⁺ ions. So, the hydrides behave as reducing agent. Their reducing nature increases down the group

It is defined as the force per area (or) the force divided by the area to which the force is applied.
Unit: Nm^-2 (or) Kgm^-1S^-2

We will use the ideal gas equation for this calculation as below:
\({P=nRT\over V}={{2mol\times 0.0821Latm.K^{-1}.mo^l{-1}\times (70+273K)}\over{6dm^3}}\)
= 9.39 atm.

When diffusing gases are at different pressures (P_A,P_B),
\(\frac{r_A}{r_B}=\frac{P_A}{P_B}\sqrt{\frac{M_B}{M_A}}\)
Where r_A and r_B are the rates of diffusion of A and B and the M_A and M_B are their respective molecular masses.

\(\frac{r_A}{r_B}=\sqrt{\frac{M_B}{M_A}}\)
r_A and r_B rates of diffusion of gases A and B and the M_A and M_B are their molecular weighs.

Beryllium hydroxide is amphoteric in nature as it reacts with both acid and alkali.
Be(OH)₂ + 2NaOH ⟶ Na₂BeO₂ + 2H₂O
Be(OH)₂ + 2HCl ⟶ BeCl₂ + 2H₂O

Li₂CO₃ is considerably less stable and decomposes readily.
\(Li_{ 2 }{ CO }_{ 3 }\overset { \triangle }{ \rightarrow } Li_{ 2 }O+{ CO }_{ 2 }\)
This is presumably due to large size difference between Li⁺ and CO₂^-3 which makes the crystal lattice unstable.

It is defined as the force exerted by a gas on unit area of the wall
\(Pressure=\frac { Force }{ Area } \)
The SI unit of pressure is the Pascal (Pa), named after the French Mathematician and Physicist Blaise Pascal, and
1 Pa = 1 N m^-2
1 N = 1 Kg m s^-2

Mg (OH)₂ ; Magnesium hydroxide.

Efflorescence is the spontaneous loss of water by a hydrated salt, which occurs when the aqueous vapor pressure of the hydrate is greater than the partial pressure of the water vapour in the air. This is the property of salts
Ex: Glauber's salt- Na₂SO₄·10H₂O
Epsom salt - MgSO₄·7H₂O

Astronauts must wear space suits filled with air, whenever they leave a space craft and are exposed to the environment of space.
Dangers experienced on moon's space :
1. In space there is no air to breathe and no air pressure.
2. Space is extremely cold and filled with dangerous radiations.
3. If they do not wear space suits, there may be bleeding due to high body pressure.
4. The space suits prevent astronauts from impacts of small bits of space dust.
5. There is no atmosphere on the moon and there are dangers from micro-meteorite impacts.
6. The astronauts are protected from these dangers on wearing space suits.