STD 11 -p-Block elements - I — NEET STD 11 Science — Question

$Cr _{2} O _{7}^{2-}+14 H ^{+}+6 e ^{-} \rightarrow 2 Cr ^{3+}+7 H _{2} O$

The amount of $Cr ^{3+}$ obtained was $0.104\, g$. The

efficiency of the process(in\%) is

(Take : $F =96000\, C$, At. mass of chromium $=52$ )

$A + O_2 \to B$ ;

$B + O_2 + H_2O \to C$

$A, B$ and $C$ are

$1.$   Among the following, the correct statement is

$(A)$ Phosphates have no biological significance in humans

$(B)$ Between nitrates and phosphates, phosphates are less abundant in earth's crust

$(C)$ Between nitrates and phosphates, nitrates are less abundant in earth's crust

$(D)$ Oxidation of nitrates is possible in soil

$2.$   Among the following, the correct statement is

$(A)$ Between $\mathrm{NH}_3$ and $\mathrm{PH}_3, \mathrm{NH}_3$ is better electron donor because the lone pair of electrons occupies spherical ' $\mathrm{s}$ ' orbital and is less directional

$(B)$ Between $\mathrm{NH}_5$ and $\mathrm{PH}_5, \mathrm{PH}_5$ is better electron donor because the lone pair of electrons occupies $\mathrm{sp}^3$ orbital and is more directional

$(C)$ Between $\mathrm{NH}_3$ and $\mathrm{PH}_3, \mathrm{NH}_3$ is a better electron donor because the lone pair of electrons occupies $\mathrm{sp}^3$ orbital and is more directional

$(D)$ Between $\mathrm{NH}_3$ and $\mathrm{PH}_3, \mathrm{PH}_3$ is better electron donor because the lone pair of electrons occupies spherical ' $\mathrm{s}$ ' orbital and is less directional

$3.$  White phosphorus on reaction with $\mathrm{NaOH}$ gives $\mathrm{PH}_3$ as one of the products. This is a

$(A)$ dimerization reaction

$(B)$ disproportionation reaction

$(C)$ condensation reaction

$(D)$ precipitation reaction

Give the answer question $1,2$ and $3.$

$(a)$ $AgF$ is soluble and colourless is aqueous medium

$(b)$ For $LiF$ solubility and Melting point both are lower as compair to $NaF$

$(c)$ Solubility of $Rb_2SO_4$ is less as compair to $BaSO_4$

$(d)$ If $AgI$ is added to water colour of water will turned yellow from colourless