MCQ
Percentage of lead in lead pencil is
- ✓$0$
- B$20$
- C$80$
- D$70$
Hence, $0 \,\%$ of lead are present in pencil.
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$H _2 O ( g ) \rightarrow H _2( g )+\frac{1}{2} O _2( g )$
The percent of water decomposing at $2300\,K$ and $1\,bar$ is $...........$ (Nearest integer).
Equilibrium constant for the reaction is $2 \times 10^{-3}$ at $2300\,K$
($A$) tetranuclear $\left[\mathrm{B}_4 \mathrm{O}_5(\mathrm{OH})_4\right]^{2-}$ unit
($B$) all boron atoms in the same plane
($C$) equal number of $s p^2$ and $s p^3$ hybridized boron atoms
($D$) one terminal hydroxide per boron atom