TS EAMCET 2018 :: Chemistry :: General questions

• Chemistry - General questions

28 g KOH is required to completely neutralise $CO_{2}$ produced on heating 60 g of imnpure $CaCo_{3}$ .The percentage  purity  of $CaCO_{3}$ is approximately  (molar mass of KOH and $CaCO_{3}$  are 56 and 100 g mol^-1, repectively)

Answer:

Explanation:

The  given relation  $CaCO_{3}$  $\underrightarrow{2KOH}$   $CO_{2}$

                                                          $\triangle$

means, 

2 moles of KOH will neutralise 1 mole of  $CO_{2}$ , given

 (i)  KOH (used)=28g

(ii) Molar mass of KOH (M=56g

 (iii) MOlar mass of $CaCO_{3}$ =100g

(iv)  Impure $CaCO_{3}$=60g

 $\because$  112g(56x2) of KOH wil neutralise=100g of $CaCO_{3}$

$\therefore$  28g KOH will neutralise= $\frac{100 \times 28}{112}$

=25g of $CaCO_{3}$

Also,

$\because$ 60g(impure) of $CaCO_{3}$. has 25g pure $CaCO_{3}$,

$\therefore$ 100g(impure) $CaCO_{3}$ has pure $CaCO_{3}$

  =$\frac{25 \times 100}{60}=41.6g$

1 mole of gas A and 1 mole of gas B at $27^{0}$C were pumped  into a 24.6 L volume pre-evacuated  isolated flask.The catalyst coated  inside the flask  catalyses the following  reaction

 $A(g)+B(g)\rightarrow  2D(g)$ .The kinetic energy  of D is 98.03l atm. Calculate the pressure relaised at the end of the reaction

Answer:

Explanation:

Kinetic energy for n moles  is given by

$K.E=\frac{3}{2}pV$

where, p is the pressure excerted by the gas and v is the volume occupied by gas

$A(g)+b(g) \rightarrow 2D(g)$

 given, Kinetic energy of D =98.03 L atm

$\therefore$  K.E= $\frac{3}{2}pV$

98.03 L atm= $\frac{3}{2} \times p \times 24.6 L$

 p=2.66 atm

Statement (A) $CO_{2}$ has no dipole moment , whereas $SO_{2}$ and   $H_{2}O$ have dipole moment .

Statement (B)  $SnCl_{2}$ is ionic , whereas $SnCl_{4}$ is covalent,

Which of the following is correct?

Answer:

Explanation:

 $CO_{2}$ is non-polar where as $SO_{2}$ and $H_{2}O$  are polar 

 $SnCl_{2}$ is ionic in an aqueous medium whereas, $SnCl_{4}$ is covalent due to the greater covalency of Sn

The correct option for the first ionisation enthalpy (in kJ mol^-1) of Li, Na, K and Cs respectively is

Answer:

Explanation:

 First ionisation enthalpy increases with smaller size. Li is the smallest. so  Li has the highest first ionisation enthalpy

Li > Na> K> Cs

The following plot represents the de-Broglie  wavelength as a function of the kinetic energy (K.E) of two particles A and B ,Identify the correct relation 

Answer:

Explanation:

 E=K.E         $hv=\frac{1}{2}mv^{2}$         $h \frac{c}{\lambda}=\frac{1}{2}mv^{2}$

 As increasing mass of particle

 slope of $\lambda$ vs $\sqrt{\frac{1}{K.E}}$ decreases.

• Chemistry - General questions