CBSE 11TH CHEMISTRY - Online Test
Q1. Correct expression for mass number A is
Answer : Option D
Explaination / Solution:
Mass number. The mass number (symbol A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus.
mass No. = no. of protons + no. of neutrons.
Q2. Troposphere is a region of the atmosphere which contains :
Answer : Option D
Explaination / Solution:
Troposphere is the lowest layer of the atmosphere where all living beings including humans live. It also has air, much water vapours, clouds and is turbulent in nature.
Q3. In the earth’s atmosphere, hydrogen exists in the form of
Answer : Option D
Explaination / Solution:
In the combined form it constitutes 15.4% of the earth crust and the ocean.
Q4. When a gas phase atom in its ground state gains an electron. This is called
Answer : Option B
Explaination / Solution:
Electron gain enthalpy (ΔegH) is defined as the enthalpy change associated with an isolated gaseous atom (X) when it gains an electron to form its corresponding anion. The reaction can be given as below:
On the basis of nature of the element, the process of accepting electron in an atom can either be exothermic or endothermic.
Q5. One of the following is highly radioactive
Answer : Option A
Explaination / Solution:
Fr is highly radioactive metal, that decays in to astatine,,radium and radon , it is also highly unstable element found only in trace amount on earth.
Q6. In general, in the molecules containing multiple bonds,_____ provide the most reactive centres. Choose the most appropriate one.
Answer : Option A
Explaination / Solution:
pie bonds are the most reactive centers.
Q7. SI units for Base Physical Quantities of length, mass and current are
Answer : Option D
Explaination / Solution:
The International System of units ( abbreviated as SI ) is modern form of metric system , and is most widely used form of measurements .
It comprises of a coherent system of measurement built of seven base units .
The base units for length , mass and current in this system of measurements are , " meter , kilogram , ampere " ,symbolised respectively as as
m ,kg , A
Q8. Three states of matter are the result of?
Answer : Option D
Explaination / Solution:
Three states of matter are the result of balance between intermolecular forces and the thermal energy of the molecules. These two factors differentiate them from each other. For understanding, The strongest intermolecular forces are in solid then in liquid and weakest in gases.
Q9. The boiling point of water at atmospheric pressure
Answer : Option C
Explaination / Solution:
Water and water vapour are in equilibrium position at atmospheric pressure (1.013 bar) and at 100°C in a closed vessel. The boiling point of water is 100°C at 1.013 bar pressure. For any pure liquid at one atmospheric pressure (1.013 bar), the temperature at which the liquid and vapours are at equilibrium is called normal boiling point of the liquid. Boiling point of the liquid depends on the atmospheric pressure.
Q10. The number of possible conformational isomers of ethane is
zero
two
Explanation:
conformational isomers are obtained by rotation about a carbon-carbon single bond.This results in infinite number of momentary arrangements of atoms in space.Hence for ethane infinite number of conformations are possible.
Answer : Option A
Explaination / Solution:
conformational isomers are obtained by rotation about a carbon-carbon single bond.This results in infinite number of momentary arrangements of atoms in space.Hence for ethane infinite number of conformations are possible.
