Chemistry

(c) 3 Glycerol (propane-1,2,3-triol), $\mathrm{CH_2OH{-}CHOH{-}CH_2OH}$, has three –OH groups.

(b) 60 Solubility is the mass of solute that dissolves in 100 g of solvent at a given temperature. $\text{Solubility}=\frac{24}{40}\times 100 = 60$

(d) ammonia Ammonia is extremely soluble in water. In the fountain experiment, a few drops of water in the flask dissolve the gas, the pressure falls, and water rushes up through the jet as a fountain. The ammonia solution turns red litmus blue (or phenolphthalein pink), showing it is basic.

(a) carbon Diamond, graphite and fullerenes are allotropes of carbon, differing in the arrangement of carbon atoms. In diamond each carbon is bonded to four others in a tetrahedral network.

(a) atomic number

The Modern Periodic Law (Moseley) states that the properties of elements are periodic functions of their atomic numbers.

(d) Li

Lithium has density about $0.53\ \text{g/cm}^3$, the lowest of all metals; Ag, Au and Pt are very dense.

(b) Ni

In the hydrogenation of vegetable oils, finely divided nickel is the catalyst, converting unsaturated oils into saturated fats (vanaspati ghee) at about 150-200 °C.

(c) $\mathrm{NH_3}$

Blue prints (diazo/ozalid prints) are developed by exposing the exposed paper to ammonia vapour.

(c) Ca > Mg > Be

Reactivity of alkaline earth metals increases down the group as atomic size increases and the outer electrons are lost more easily, so Ca > Mg > Be.