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questions
List of practice Questions
The coefficient of
x
n
in the expansion of
e
7
x
+
e
x
e
3
x
is
WBJEE
Mathematics
Differential equations
Which one of the following alcoholic drinks is produced without distillation ?
Biology
Microbes in human welfare
Effective nuclear charge
$\left(Z_{eff} \right)$
for a nucleus of an atom is defined as
Chemistry
Structure of atom
Which one is the correct summary equation of photosynthesis?
Biology
Photosynthesis in higher plants
Which of the following is the hydrophobic synthetic acrylate polymer that has glass-transition temperature of about 10°C?
WBJEE
Chemistry
Solutions
In a reaction carried out at 400 K, 0.01% of the total collisions are effective. What is the energy of activation of the reaction?
WBJEE
Chemistry
Structure of atom
Consider the following metallurgical processes:(A) Heating impure metal with CO and distilling the resulting volatile carbonyl compound, which is finally decomposed at 150
o
C - 200
o
C to get pure metal.(B) Heating the sulphide ore in air until a fraction of it is converted to its oxide and then further heating in the absence of air to allow the oxide to react with unchanged metal sulphide and reduce it to the metallic state.(C) Electrolysis of the molten electrolyte containing approximately equal amounts of the metal chloride and NaCl to obtain the metal.The processes used for obtaining Mg, Ni and Cu, respectively, are
WBJEE
Chemistry
Structure of atom
A solid sphere of uniform density and radius
$R$
applies a gravitational force of attraction equal to
$F_{1}$
on a particle placed at
$P$
, distance
$2 \, R$
from the centre O of the sphere. A spherical cavity of the radius
$R/2$
is now made in the sphere as shown in the figure. The sphere with the cavity now applies a gravitational force
$F_{2}$
on the same particle placed at
$P$
. The ratio
$F_{2}/F_{1}$
will be
Physics
Gravitation
The percentage by volume of C3H8 in a mixture of C3H8, CH4 and CO is 36.5. Calculate the volume of CO2 produced when 100 ml of the mixture is burnt in excess of O2.
WBJEE
Chemistry
Alcohols, Phenols and Ethers
A radioactive nucleus undergoes a series of decay according to the scheme
$ {A ->[\alpha] A1}$
$ { ->[\beta] A2}$
$ { ->[\alpha] A3}$
$ { ->[\gamma] A4}$
If the mass number and atomic number of A are 180 and 72 respectively, these numbers of
$A_4$
are
Physics
Nuclei
The equivalent resistance of the circuit, across
$AB$
is given by
Physics
Current electricity
A problem is given to 3 students. Their chances of solving it individually are
$\frac{1}{3}, \frac{1}{4}$
and
$\frac{1}{5}$
. The probability that the problem will be solved is
Mathematics
Conditional Probability
$E^{\circ}$
values of three metals are listed below.
$Zn^{2+}_{\left(aq\right)}+2e^{-} \to Zn_{\left(s\right)};\quad E^{\circ}=-0.76\,V$
$Fe^{2+}_{\left(aq\right)}+2e^{-} \to2Fe_{\left(s\right)}; \quad E^{\circ}=-0.44\,V$
$Sn^{2+}_{\left(aq\right)}+2e^{-} \to Sn_{\left(s\right)}; \quad E^{\circ}=-0.14\,V$
Which of the following statements are correct on the basis of the above information? (i) Zinc will be corroded in preference to iron if zinc coating is broken on the surface. (ii) If iron is coated with tin and the coating is broken on the surface then iron will be corroded. (iii) Zinc is more reactive than iron but tin is less reactive than iron.
Chemistry
Electrochemistry
$E=-\frac{dV}{dr}$
here negative sign sigified that
Physics
electrostatic potential and capacitance
Seven resistances are connected as shown in the given figure. The equivalent resistance between A and B is
Physics
Current electricity
Five equal resistances each of resistance
$R$
are connected as shown in the figure. A battery of
$V$
volts is connected between
$A$
and
$B$
. The current flowing in
$AFCEB$
will be
Physics
Current electricity
A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength
$20 \, Vm^{-1} $
and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons?
Physics
Moving charges and magnetism
The more positive the value of
$E^{\circ}$
, the greater is the tendency of the species to get reduced. Using the. standard electrode potential of redox couples given below find out which of the following is the strongest oxidising agent.
$E^{\circ}$
values :
$Fe^{3+}/Fe^{2+} = + 0.77; I_{2\left(s\right)}/I^- = + 0.54$
;
$Cu^{2+}/Cu = + 0.34$
;
$Ag^{+}/Ag = + 0.80\, V$
Chemistry
Classical Idea Of Redox Reactions – Oxidation And Reduction Reactions
A positively charged particle is released from rest in a uniform electric field. The electric potential energy of the charge
Physics
electrostatic potential and capacitance
A satellite is revolving round the earth with orbital speed
$v_0$
. If it stops suddenly, the speed with which it will strike the surface of earth would be (
$v_e= $
escape velocity of a body on earth's surface)
Physics
Gravitation
During osmosis, water moves through a membrane
Biology
Transport in Plants
If the sums of n terms of two arithmetic series are in the ratio 2n + 3 : 6n + 5, then the ratio between their 13
th
terms is
WBJEE
Mathematics
Sequence and series
The solubility product of silver chromate is
$4 \times 10^{-12}$
. The molar solubility of the salt is
Chemistry
Solutions
The line passing through the points
\((2,1,0) , (5,0,1)\)
and
\( (4,1,1)\)
intersects the
\(x-\)
axis at
Mathematics
Lines
During osmosis,flow of water through a semipermeable membrane is
Chemistry
Solutions
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