TS EAMCET 2017 :: Chemistry :: General questions

• Chemistry - General questions

The species having a pyramidal shape according to VSEPR theory is 

Answer:

Explanation:

$OsF_{2}$ central atom sulphur contain 3 b.p and 1 l.p hence, $OsF_{2}$ is pyramidal . But it is  given as $OsF_{2}$

$\therefore$ It is wrong question 

Which among the following is the strongest acid?

Answer:

Explanation:

Among the hydrogen halides, the strongest acids is HI

As the size of halogen increase, bond length

increase hence bond energy decreases

So,  the HI  releases $H^{\oplus}$ ions easily and slow high acidic nature.

 Given $\triangle H _{f}^{0}$  for $CO_{2} (g)$ , $CO(g)$ and $H_{2}O(g)$  are -393.5 ,-110.5 and -241.8 kJ  mol^-1, respectively . The $\triangle H_{f}^{0}$  [in  k J mol^-1] for the reaction

$CO_{2}(g)+H_{2}(g) \rightarrow  CO(g)+H_{2}O(g)$ is 

Answer:

Explanation:

$CO_{2}(g)+H_{2}(g) \rightarrow  CO(g)+H_{2}O(g)$

$\triangle H_{f}^{0}= (\triangle  H)_{products}-(\triangle H)_{reactants}$

Hence, 

$\triangle H_{f}^{0}=[\triangle H_{fCO}+\triangle H_{fH_{2}O}]-[\triangle H_{fCO_{2}}].....(i)$

 Given,   $\triangle H_{fCO_{2}(s)}=-393.5kJmol^{-1}$

$\triangle H^{0}_{fC0}=-110.5kJmol^{-1}$

$\triangle H^{0}_{fH_{2}O}=-241.8kJmol^{-1}$

Put there value in equation(i)

$\triangle H_{f}^{0}$=-110.5-241.8+393.5=41.2

The number of complementary hydrogen bond (s)  between a guanine and cytosine pair is 

Answer:

Explanation:

 The number of hydrogen bonds between adenine and thymine are two  (A=T) whereas the number of hydrogen  bond between guanine and cytosine are three (G≡ C)

Which of the following elements has the lowest melting point ?

Answer:

Explanation:

The melting  point order of IV A group elements is 

C > Si > Ge > Pb > Sn

• Chemistry - General questions