Answer:
we know, at STP ( standard temperature and pressure).
we know, volume of 1 mole of gas = 22.4L
weight of 1 Litre of hydrogen gas = 0.09g
so, weight of 22.4 litres of hydrogen gas = 22.4 × 0.09 = 2.016g ≈ 2g = molecular weight of hydrogen gas.
similarly,
weight of 2L of a gas = 2.88gm
so, weight of 22.4 L of the gas = 2.88 × 22.4/2 = 2.88 × 11.2 = 32.256g
hence, molecular weight of the gas = 32.256g
vapor density = molecular weight/2
= 32.256/2 = 16.128g
hence, vapor density of the gas is 16.128g.
Explanation:
Answer: 
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Precipitation is a type of displacement reaction in which one the products is formed in the solid state.

The number of moles of a gas if it occupy a volume of 4dm at 10 atm and - 200 c is 6.67 moles
calculation
by use of ideal gas equation
that is PV =nRT
where P(pressure) = 10 atm
V( volume) = 4dm^3 = 4L
n(number of moles) =?
R(gas constant) = 0.0821 L.atm/mol.K
T = -200 +273 = 73 K
make n the formula of the subject n = PV/RT
n is therefore = (10 atm x 4l)/(0.0821 L.atm/mol.K x 73 K) = 6.67 moles
Calcium Hydroxide (Ca(OH)2) or slaked lime is a base because in aqueous solution of slaked lime there are hydroxide ions available due to the dissociation of electrolyte (Ca(OH)2).