1
Q:

# If people sleep in closed rooms where charcoal fire is burning , they die due to

 A) carbon monoxide B) carbon dioxide C) methane D) phosgene

Explanation:

A closed room is aplace where charcoal is burnt in limited supply of air. There is every chance for the formation of the deadly poisonous carbon monoxide, which when inhaled, reacts with the iron in haemoglobin of blood and prevents the supply of oxygen. It is said to be treacherous as there can be no previous warning of its presence because it is an odourless and colourless gas.

Subject: Chemistry
Q:

Silver Mirror test is given by which one of the following compounds?

1. Benzophenone

2. Acetaldehyde

3. Acetone

4. Formaldehyde

 A) only 1 B) Only 2 C) 1 and 3 D) 2 and 4

Explanation:

Both Formaldehyde and Acetaldehyde will give this test

$\inline \dpi{100} \fn_jvn \small HCHO\xrightarrow[]{[Ag(NH_{3})_{2}^+]}\begin{matrix} Ag\\ Silver\: mirror \end{matrix}+Organic\: compound$

$\inline \dpi{100} \fn_jvn \small CH_{3}-CHO\xrightarrow[]{[Ag(NH_{3})_{2}^+]}\begin{matrix} Ag\\ Silver\: mirror \end{matrix}+Organic\: compound$

Filed Under: Chemistry
Exam Prep: AIEEE

0 18
Q:

The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 $\inline \dpi{100} dm^{3}$ at 27°C is to a volume of 100 $\inline \dpi{100} dm^{3}$

 A) 42.3 J/ mole / K B) 38.3 J/ mole / K C) 35.8 J/ mole / K D) 32.3 J/ mole / K

Explanation:

$\inline \dpi{100} \Delta s=nRln\frac{V_{2}}{V_{1}}$

$\inline \dpi{100} \Delta s=2.303\times 2\times 8.314\log \frac{100}{10}$

$\inline \dpi{100} \Delta s=38.3\: J/mole/K$

Filed Under: Chemistry
Exam Prep: AIEEE

1 18
Q:

A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emissions is at 680 nm, the other is at :

 A) 518 nm B) 1035 nm C) 325 nm D) 743 nm

Explanation:

$\inline \dpi{100} \frac{1}{\lambda }=\frac{1}{\lambda _{1}}+\frac{1}{\lambda _{2}}$

$\inline \dpi{100} \frac{1}{355}=\frac{1}{680}+\frac{1}{\lambda _{2}}$

$\inline \dpi{100} \frac{1}{\lambda _{2}}=\frac{680-355}{355\times 680}$

$\inline \dpi{100} \Rightarrow \lambda _{2}=743\: nm$

Filed Under: Chemistry
Exam Prep: AIEEE

0 16
Q:

In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is

$\inline \dpi{100} \small 1.\: A_{2}B_{5}$

$\inline \dpi{100} \small 2.\: A_{2}B$

$\inline \dpi{100} \small 3.\: AB_{2}$

$\inline \dpi{100} \small 4.\: A_{2}B_{3}$

 A) Option 1 B) Option 2 C) Option 3 D) Option 4

Explanation:

$\inline \dpi{100} \small Z_{A}=\frac{8}{8}\; \; Z_{B}=\frac{5}{2}$

So formula of compound is $\inline \dpi{100} \small AB_{\frac{5}{2}}$

i.e., $\inline \dpi{100} \small A_{2}B_{5}$

Filed Under: Chemistry
Exam Prep: AIEEE

1 197
Q:

The degree of dissociation ($\inline \alpha$) of a weak electrolyte, $\inline A_{x}B_{y}$ is related to van't Hoff factor (i) by the expression:

$\inline 1.\: \alpha =\frac{x+y+1}{i-1}$

$\inline 2.\: \alpha =\frac{x+y-1}{i-1}$

$\inline 3.\: \alpha =\frac{i-1}{x+y+1}$

$\inline 4.\: \alpha =\frac{i-1}{x+y-1}$

 A) 1 is correct B) 2 is correct C) 3 is correct D) 4 is correct

Explanation:

$\inline \dpi{100} \fn_jvn \small Van't \: \: Hoff \: \: factor (i)=\frac{ Observed \: \: colligative\: \: property}{Normal \: \: colligative \: \: property}$

$\inline \dpi{100} \fn_jvn \small \begin{matrix} A_{x}B_{y}\\ 1-\alpha \end{matrix}\rightarrow \begin{matrix} xA^{+y}\\ x\alpha \end{matrix}+\begin{matrix} yB^{-x}\\ y\alpha \end{matrix}$

Total Moles = $\inline \dpi{100} \fn_jvn \small 1-\alpha +x\alpha +y\alpha$

$\inline \dpi{100} \fn_jvn \small =1-\alpha(x +y-1)$

$\inline \dpi{100} \fn_jvn \small i=\frac{1+\alpha(x +y-1)}{1}$

$\inline \dpi{100} \fn_jvn \small \Rightarrow \alpha =\frac{i-1}{x+y-1}$