Practice problems on JEE Mains, JEE Mains 2000

Question 1

Alkyl fluorides generally give Hoffman's elimination product. This is because

Accepted Answer

F− being a poor leaving group creates anionic character in the transition state

Answer

F− being a good leaving group creates cationic character in the transition state

Answer

F− being a poor leaving group creates cationic character in the transition state

Answer

F− being a good leaving group creates anionic character in the transition state

Question 2

Amongst BCl3​,CO3−2​,NO3−​,ClO3−​,SO3−2​,BO3−3​, AsO33−​ and SO3​, the non-planar species are

Accepted Answer

SO3−2​,ClO3−​,AsO3−3​

Answer

AsO3−3​,BCl3​,NO3−​

Answer

NO3−​,BCl3​,BO3−3​

Answer

AsO3−3​,SO3​,BCl3​

Question 3

Consider the following graph for a real gasCorrect statement is

Accepted Answer

Gas is non ideal, Z=1 at point A

Answer

Gas is ideal, Z=1 always

Answer

Gas is ideal, Z=1 at point A

Answer

Gas is non ideal, Z=1 at point A

Question 4

Select the incorrect statement about the helium.

Accepted Answer

The last electron of helium enter in 1 s orbital so it is placed with the s-block element in modern periodic table

Answer

The ionization energy of helium is highest

Answer

The electron gain enthalpy of helium is positive

Answer

Helium belongs to a group of elements, which are largest in size in respective period

Question 5

Consider the following reaction.H3​ N:+BF3​⟶H3​ N:→BF3​Which of the following change is not observed for the above reaction?

Accepted Answer

Total number of electron pairs

Answer

Hybridization

Answer

Bond angle

Answer

Shape

Question 6

3.6 g of an ideal gas was injected into a bulb of internal volume of 8 L at pressure P atm and temp T.K. The bulb was then place in a thermostat maintained at (T+15)K and 0.6 g of the gas was let off to keep the original pressure which of the following is the correct value of T and P if the molar mass of gas is 44 g/mol.

Accepted Answer

P=0.063 atm, T=75 K

Answer

P=0.062 atm,T=50 K

Answer

P=0.62 atm, T=75 K

Answer

P=6.2 atm, T=75 K

Question 7

Elements X (valence e−=3) and Y( valence e−=6) belong to same period. Then select the correct òption.

Accepted Answer

Size(X)>Size(Y)

Answer

EA(X)>EA(Y)

Answer

IE(X)>IE(Y)

Answer

EN(X)>EN(Y)

Question 8

Density (in g/L ) of CO2​ gas at S.T.P. is

Accepted Answer

1.96

Answer

19.6

Answer

22

Answer

11

Question 9

The hybridisation of boron in 1:1 complex of dimethylether and BH3​ is

Accepted Answer

Both (2) & (3)

Answer

Same of B on pure BH3​

Answer

Same as O in pure ether

Answer

Same as C in ether

Question 10

At very high pressure correct van der Waal gas equation for CO2​ is

Accepted Answer

PV=RT+Pb

Answer

PV=RT−V2a​

Answer

PV=RT

Answer

Both (1) & (2)

Question 11

Choose the incorrect pair regarding the given property

Accepted Answer

H2​O>H2​O2​ Boiling point

Answer

H2​O2​>H2​O Acidic strength

Answer

NH3​>PH3​ Basic strength

Answer

H2​ S>H2​O Acidic strength

Question 12

The root mean square speed of 4 g of He is 300 ms−1. Total kinetic energy of He gas is

Accepted Answer

180 J

Answer

360 J

Answer

120 J

Answer

90 J

Question 13

The hybridisation of central atom in I3⊕​ is

Accepted Answer

sp3

Answer

sp2

Answer

sp3d

Answer

sp3d2

Question 14

Out of the following the least electronegative is

Accepted Answer

Al

Answer

B

Answer

Ga

Answer

Ge

Question 15

The breaking of which of the following bond is most endothermic?

Accepted Answer

Cl−Cl

Answer

F−F

Answer

Br−Br

Answer

I−I

Question 16

The correct order of stability

Accepted Answer

N2​>N2+​>N2−​

Answer

N2​>N2−​>N2+​

Answer

N2+​>N2−​>N2​

Answer

N2−​>N2+​>N2​

Question 17

Consider a real gas placed in a container. If the intermolecular attractions are supposed to disappear suddenly which of the following would happen?

Accepted Answer

The pressure increases

Answer

The pressure decreases

Answer

The pressure remains unchanged

Answer

The gas collapses

Question 18

The places that were left empty by Mendeleev in his periodic table were for:

Accepted Answer

gallium and germanium

Answer

aluminium and silicon

Answer

arsenic and antimony

Answer

molybdenum and tungsten

Question 19

In a given energy level, the order of penetration effect of different orbitals is :

Accepted Answer

f<d<p<s

Answer

f<p<d<s

Answer

s<p<d<f

Answer

s=p=d=f