cbse 11th chemistry | Online Objective Test

Q1. H2O2 as an antispectic is used in the name of

A. perborate

B. perhydrol

C. bleacher

D. percarbonate

Answer : Option B
Explaination / Solution:

Perhydrol is a solution of hydrogen peroxide (H2O2) at a concentration of 30% of weight by volume(w/v) or 100 volume strength.

Perhydrol is a mild antiseptic used on the skin to prevent infection of minor cuts, scrapes, and burns. It may also be used as a mouth rinse to help remove mucus or to relieve minor mouth irritation (e.g., due to canker/ cold sores, gingivitis). This product works by releasing oxygen when it is applied to the affected area. The release of oxygen causes foaming, which helps to remove dead skin and clean the area.

Chemical Bonding and Molecular Structure Prepare / Learn

Q2. The criterion of overlap of atomic orbitals is the main factor for the formation of

A. Hydrogen bonds

B. ionic bonds

C. coordinate bonds

D. covalent bonds

Answer : Option D
Explaination / Solution:

The valence bond theory is introduced to describe bonding in organic molecules. In this model, bonds are considered to form from the overlapping of two atomic orbitals on different atoms, each orbital containing a single electron. In general, greater the overlap, stronger is the bond formed between the two atoms. Thus, according to the orbital overlap concept, atoms combine together by overlapping their orbital and thus forming a lower energy state where their valence electrons with opposite spin, pair up to form covalent bond.

The s-Block Elements Prepare / Learn

Q3. In the preparation of Sodium carbonate the by- product formed is:

A. NH4Cl

B. Ca (OH)2

C. NH3

C a C l_{2}

Answer : Option D
Explaination / Solution:

C a C l_{2}

is the by product.

Organic Chemistry Some Basic Principles and Techniques Prepare / Learn

Q4. The principle involved in paper chromatography is

A. Adsorption

B. Volatility

C. Solubility

D. Partition

Answer : Option D
Explaination / Solution:

Paper chromatography is based on the principle of partition.

States of Matter Prepare / Learn

Q5. Pressure of 1 g of an ideal gas A at 27 ∘C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at same temperature the pressure becomes 3 bar. Relationship between their molecular masses is

A. MB= 2MA

B. MB= 10MA

C. MB= 4MA

D. MB= 5MA

Answer : Option C
Explaination / Solution:

PV=(m/M)RT

Equilibrium Prepare / Learn

Q6. When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink. On the basis of this information mark the correct answer.

{[Co (H_{2} O) 6]}^{3 +} (aq) + 4C l^{-} (aq)

⇌

{[CoC l_{4}]}^{2 -} (aq) + 6 H_{2} O

(l )

A. The sign of ΔH cannot be predicted on the basis of this information.

B. ΔH< 0 for the reaction

C. ΔH> 0 for the reaction

D. ΔH= 0 for the reaction

Answer : Option C
Explaination / Solution:

This reaction is endothermic.

Redox Reactions Prepare / Learn

Q7.

2 N a^{+} (s) \to 2 N a^{+} (g) + 2 e^{-}

H 2 (g) + 2 e^{-} n ? 2 H + (g)

H 2 (g) + 2 e^{-} n ? 2 H + (g)

H 2 (g) + 2 e^{-} n ? 2 H + (g)

A. hydrogen is oxidised

B. sodium is reduced

C. electronegativity of sodium determines the direction of the reaction

D. sodium is oxidised and hydrogen is reduced

Answer : Option D
Explaination / Solution:

sodium is oxidized and hydrogen is reduced.

Some Basic Concepts of Chemistry Prepare / Learn

Q8. The gram molar mass of

C O_{2}

A. 88 g

B. 46 g

C. 44 g

D. 78 g

Answer : Option C
Explaination / Solution:

Molar mass of CO2 = $Σ$ (atomic mass of C , 2*atomic mass of O )

= [12+2(16)] u

Since , gram molar mass

= Molar mass expressed in gms .

$∴$ gram molar mass of CO2

= 44 g

Hydrocarbons Prepare / Learn

Q9. The correct IUPAC name of the following alkane is

A. 3,6 – Diethyl – 2 – methyloctane

B. 5 – Isopropyl – 3 – ethyloctane

C. 3 – Isopropyl – 6 – ethyloctane

D. 3 – Ethyl – 5 – isopropyloctane

Answer : Option A
Explaination / Solution:

Following the rules of nomenclature,the IUPAC name of the given compound is 3,6-Diethyl-2-methyloctane

Thermodynamics Prepare / Learn

Q10. The enthalpy of combustion of methane, graphite and dihydrogen at 298 K are, - 890.3 kJ mol-1, -393.5 kJ mol-1 and –285.8 kJ mol-1 respectively. Enthalpy of formation of CH4 (g) will be

A. +74.8 kJ

mo l^{- 1}

B. +52.26 kJ

mo l^{- 1}

C. -74.8 kJ

mo l^{- 1}

D. - 52.27 kJ

mo l^{- 1}

Answer : Option C
Explaination / Solution:

ΔH= -393.5 +2(-285.8)-(-890.3)

= -74.8 kJ/mo

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