MCQ
Which is not correct in case of Be and Al?
- ABoth are rendered passive by conc. HNO3.
- BCarbides of both give methane on hydrolysis.
- CBoth give hydroxides which are basic.
- DBoth give covalent chlorides.
Explanation:
Both form amphoteric hydroxide/oxide not either basic or acidic.
Because as Aluminium is in 3rd group it can either accept electron or donate hence they form oxides which are amphoteric.
The reason why beryllium forms is aluminium and beryllium has diagonal relationship.
Hence both will have common properties.
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$\Delta_f G^0[\mathrm{C}(\text { graphite })]=0 \mathrm{kJmol}^{-1}$
$\Delta_f G^0[\mathrm{C}(\text { diamond })]=2.9 \mathrm{kJmol}^{-1}$
The standard state means that the pressure should be $1$ bar, and substance should be pure at a given temperature. The conversion of graphite [C(graphite)] to diamond [C(diamond)] reduces its volume by $2 \times 10^{-6} \mathrm{~m}^3 \mathrm{~mol}^{-1}$. If $\mathrm{C}$ (graphite) is converted to $\mathrm{C}$ (diamond) isothermally at $\mathrm{T}=298 \mathrm{~K}$, the pressure at which $C$ (graphite) is in equilibrium with C(diamond), is
[Useful information: $1 \mathrm{~J}=1 \mathrm{~kg} \mathrm{~m}^2 \mathrm{~s}^{-2} ; 1 \mathrm{~Pa}=1 \mathrm{~kg} \mathrm{~m}^{-1} \mathrm{~s}^{-2} ; 1 \mathrm{bar}=10^5 \mathrm{~Pa}$ ]