cbse 11th chemistry | Online Objective Test

Q1. Cement is an industrially important compound of

A. Magnesium

B. Calcium

C. Sodium

D. Potassium

Answer : Option B
Explaination / Solution:

Cement is the important compound of Calcium.

Organic Chemistry Some Basic Principles and Techniques Prepare / Learn

Q2. The addition of HCl to an alkene proceeds in two steps. The first step is the attack of H+ ion to portion which can be shown as

A. (iv)

B. (i)

C. (ii)

D. (jjj)

Answer : Option C
Explaination / Solution:

arrows are shown in the direction of movement of electrons.

States of Matter Prepare / Learn

Q3. A person living in Shimla observed that cooking food without using pressure cooker takes more time. The reason for this observation is that at high altitude:

A. temperature increases

B. pressure increases

C. pressure decreases

D. temperature decreases

Answer : Option C
Explaination / Solution:

As we move to higher altitude P decreases.

Some Basic Concepts of Chemistry Prepare / Learn

Q4. Chemistry does not play a major role in

A. Explaining superconductivity

B. Design and synthesis new materials having specific magnetic, electric and optical properties.

C. Explaining ozone depletion

D. Large scale production of a variety of fertilizers

Answer : Option A
Explaination / Solution:

Chemistry does not deal in explaining superconductivity.

*In superconducting materials the charecteristics of superconductivity appear when the temperature is lowered below a critical temperature.

*The onset of superconductivity is accompanied by abrupt changes in physical properties which are more related to phase transitions of the material .

These aspects of studies in properties of materials are better related to studies in the fields of Physics , eventhough principles involved in Chemistry & Physics go hand to hand.

Equilibrium Prepare / Learn

Q5.

The ionization constant of acetic acid is

1 . 74 x 1 0^{- 5}

. Calculate the degree of dissociation of acetic acid in its 0.05 M solution. Calculate the concentration of acetate ion in the solution and its pH.

A. 0.00013M and pH 3.03

B. 0.00093M and pH 3.03

C. 0.00193M and pH 3.03

D. 0.00203M and pH 3.03

Answer : Option B
Explaination / Solution:

Ka =

C α^{2}

and pH=-log(Cα).

Hydrocarbons Prepare / Learn

Q6.

In the following sequence of reactions, the alkene is converted to compound $B$

$C H_{3} CH = CHC H_{3} \overset{O_{3}}{\to} A \overset{H_{2} O, Z n}{\to} B$

The compound $B$ is --------- ?

A. CH3 CHO

B. CH3CH2COCH3

C. CH3COCH3

D. CH3CH2CHO

Answer : Option A
Explaination / Solution:

The given sequence of conversion steps represent Ozonolysis of 2-Butene , which follows the following path ,

1 . Formation of an unstable intermediate / ozonide $(A)$

2 . Cleavage of the intermediate / ozonide by $(Z n + H_{2} O)$ to smaller molecules , giving out the compound $B$ , which is CH3 CHO ( Ethanal )

The reaction is well depicted as below ,

Redox Reactions Prepare / Learn

Q7. Which of the following elements does not show disproportionation tendency?

A. Br

B. Cl

C. F

D. I

Answer : Option C
Explaination / Solution:

F (Fluorine) is most electronegative element so it always show -1 oxidation state.

Classification of Elements and Periodicity in Properties Prepare / Learn

Q8. An ionic compound is expected to have tetrahedral structure if

\frac{r_{+}}{r_{-}}

lies in the range of

A. 0.225 to 0.414

B. 0.155 to 0.225

C. 0.732 to 1

D. 0.414 to 0.732

Answer : Option A
Explaination / Solution:

For tetrahedral

\frac{r_{+}}{r_{-}}

lies in the range 0.225 to 0.414.

Environmental Chemistry Prepare / Learn

Q9. The ozone layer found high in the stratosphere:

A. Is toxic to plants

B. Protects against the suns harmful UV rays

C. Is capable of disintegrating fabric and rubber

D. Can react with atmospheric pollutants to form smog

Answer : Option B
Explaination / Solution:

The ozone layer found high in the stratosphere Protects against the suns harmful UV rays

Structure of Atom Prepare / Learn

Q10.

How many protons, neutrons and electrons are in $^{56} F e^{3 +}$ ?

A. 26 protons, 30 neutrons, 23 electrons

B. 26 protons, 30 neutrons, 26 electrons

C. 23 protons, 33 neutrons, 20 electrons

D. 23 protons, 33 neutrons, 26 electrons

Answer : Option A
Explaination / Solution:

Atomic number of iron (Fe) = 26

So number of protons = 26

Number of protons = number of electrons

But To gain 3+ charge it should loose 3 electron. So number of electrons present = 26-3 = 23

Now atomic mass = 56 (Given).

Number of neutrons = atomic mass - number of protons = 56-26 = 30

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