CBSE 11TH CHEMISTRY - Online Test
Q1. During the formation of a chemical bond
Answer : Option C
Explaination / Solution:
A chemical bond is a lasting attraction between atoms that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between atoms with opposite charges, or through the sharing of electrons as in the covalent bonds.
When a bond forms, electrons are attracted to the space between nuclei where the electrostatic force of attraction is greater. As the electrons fall to a position of lower potential energy, the total mechanical energy of the molecular system decreases. Part of the mechanical energy of the unbound atoms is lost when they form the molecular system with a lower total mechanical energy.
Lower the energy higher the stability of bond.
Q2. Caustic soda is
Answer : Option A
Explaination / Solution:
Caustic Soda is NaOH.
Q3. In organic compounds, when homolytic cleavage takes place, one of the electrons of the shared pair in a covalent bond goes with each of the bonded atoms. This results in the formation of
Answer : Option D
Explaination / Solution:
free radicals are formed by hemolytic cleavage.
Q4. What will be the pressure of the gaseous mixture when 0.5 L of at 0.8 bar and 2.0 L of dioxygen at 0.7 bar are introduced in a 1L vessel at?
Answer : Option C
Explaination / Solution:
x1=0.8x0.5 x 1=0.7x2 And P=+
Q5. and are the respective ionisation constants for the following reactions.
The correct relationship between and is
The correct relationship between and is
Answer : Option B
Explaination / Solution:
Equation (3) =(1) + (2) So = ×
Q6. Hydrogen is prepared from H2O by adding
Answer : Option D
Explaination / Solution:
Calcium is a silvery-white metal; it is relatively soft, but much harder than sodium metal. Calcium is a member of the alkaline-earth metals (Group II on the periodic table); these metals react vigorously with water, although not as violently as the Group I metals such as sodium or potassium:
Ca(s) + 2H2O(l) ——> Ca(OH)2(aq) + H2(g)
Q7. The molar mass of is
Answer : Option D
Explaination / Solution:
Molar mass of Ag NO3
= [ atomic mass of Ag + atomic mass of N + 3 ( atomic mass of O ) ) ] u
Substituting the atomic masses of Ag , N & O as 107.9 , 14 & 16 ,respectively in the above expression we get -
=
=169.9 u
Q8. Arrange the following carbanions in order of their decreasing stability.(A) H3C – C C– (B) H – C ≡ C– (C)
Answer : Option D
Explaination / Solution:
In B,the '-' charge is on sp hybridised C atom so the negative charge is stabilised.In A,there is an alkyl group attached to sp hybridised carbon which destabilises the negative charge. In C,the '-' charge is on a sp3 hybridised carbon and is hence the least stable.
Q9. The reaction of cyanamide, NCN (s), with dioxygen was carried out in a bomb calorimeter, and was found to be 742.7 kJ at 298 K. Calculate enthalpy change for the reaction at 298 K. NCN(g) +
Answer : Option B
Explaination / Solution:
RT where Δng = 2-((3/2)+1)
Q10. The correct order for the decrease in atomic radii is
Answer : Option D
Explaination / Solution:
In a period moving from left to right, the effective nuclear charge increases because the next electron fills in the same shell. So the atomic size decreases.
