Alkali metal ions are-
1. Diamagnetic and colored
2. Diamagnetic and colorless
3. Paramagnetic and colored
4. Paramagnetic and colorless
The compound X on heating gives a colourless gas. The residue is dissolved in water to obtain Y. Excess of is bubbled through aqueous solution of Y, Z is formed. Z on gentle heating gives back X. The compound X is-
Magnesia can be prepared by-
(A) Burning Mg in air
(B) By heating hydroxide, nitrate, sulphate or carbonate of magnesium
(C) By heating Mg in steam
(D) All of these
Insoluble compound in acetic acid is-
(A) Calcium oxide
(B) Calcium carbonate
(C) Calcium oxalate
(D) Calcium hydroxide
Assertion : LiF is almost insoluble in water
Reason : LiCl is soluble not only in water but also in acetone.
Assertion : s-block elements do not occur free in nature
Reason : s-block elements are highly electropositive in nature.
Assertion : Potassium and caesium are useful as electrodes in photoelectric cells.
Reason : Potassium and caesium, when irradiated with light, the light energy absorbed is sufficient to eject out the electron from an atom.
Assertion : The alkaline earth metals have much higher melting and boiling points than those of the alkali metals.
Reason : The melting and boiling points of alkaline earth metal do not vary in a regular fashion.
Assertion : The ionisation enthalpies of alkaline earth metals are fairly low.
Reason : In general, the low ionisation enthalpies of alkaline earth metals are due to large size of their atoms.
Assertion : The magnitude of the hydration enthalpies of alkaline earth metal ions () are much larger than those for the alkali metal ions.
Reason : The magnitude of hydration enthalpy depends upon the square of the charge on the ion.