VITEEE 2014 :: Chemistry :: General questions

• Chemistry - General questions

Which has the smallest size?

Answer:

Explanation:

$P^{5+}$ having maximum nuclear charge per electron. Therefore, its size is the smallest 

Purest form of iron is 

Answer:

Explanation:

The purest  form of iron  isd wrought  or malleable 

The half-life of two samples are 0.1 and 0.8 s. Their respective concentration are 400 and 50 respectively . The order of the reaction is 

Answer:

Explanation:

It is known

 $\frac{(t_{1/2})_{1}}{(t_{1/2})_{2}}=\left[\frac{a_{2}}{a_{1}}\right]^{(n-1)}$

 Here, n= order of reaction

 Given, $ (t_{1/2})_{1}=0.1 s, a_{1}=400$

 $(t_{1/2})_{2}=0.8 s, a_{2}=50$

 On putting the values 

 $\frac{0.1}{0.8}=\left[\frac{50}{400}\right]^{(n-1)}$

 Taking log on both sides,

 $\log \frac{0.1}{0.8}=(n-1) \log \frac{50}{400}$

  $\log \frac{1}{8}=(n-1)\log \frac{1}{8}$

$n-1=1 \Rightarrow n=2$

The equivaent conductivity of a solution containing 2.54 g of $CuSO_{4}$ per L is 91.0 $W^{-1} cm^{2} eq^{-1}$ . Its conductivity would be 

Answer:

Explanation:

We know that,

  $k=\wedge_{eq}.C$

Given,  $\wedge eq=91.0 \Omega^{-1}cm^{2} eq^{-1}$

$k=(91 \Omega^{-1} cm^{2} eq^{-1})$

                                           $\left(\frac{2.54}{159/2\times1000}eq.cm^{-3}\right)$

 $=2.9 \times 10^{-3}\Omega^{-1}cm^{-1}$

The solubility  product of$ Ag_{2}CrO_{4}$ is $32 \times 10^{-12}$ . What is the concentration  of $CrO_{4}^{-}$ ions in that solution?

Answer:

Explanation:

$Ag_{2}CrO_{4} \rightarrow 2Ag^{+}+CrO_{4}^{2-}$

  S                                     2S               S

$K_{SP}=(2s)^{2}s=4s^{2}s=4s^{3}$

    $S=\left(\frac{K_{sp}}{4}\right)^{1/3}\Rightarrow\left(\frac{32\times10^{-12}}{4}\right)^{1/3}=2\times10^{-4}M$

• Chemistry - General questions