CBSE 11TH CHEMISTRY - Online Test
Q1.
The formation of the Cl2 molecule can be understood in terms of the sharing of a pair of electrons between the two chlorine atoms, each chlorine atom contributing one electron to the shared pair. Choose the most appropriate name of the bond that is formed
Answer : Option D
Explaination / Solution:
Two chlorine atoms will each share one electron to get a full outer shell and form a stable Cl2 molecule.
By sharing the two electrons where the shells touch each chlorine atom can count 8 electrons in its outer shell. These full outer shells with their shared electrons are now stable and the Cl2 molecule will not react further with other chlorine atoms. One pair of shared electrons form a single covalent bond.
Q2. Sodium and potassium belong to the category of
Answer : Option B
Explaination / Solution:
Na and K are shiny, soft ,highly reactive metal at standard temprature and pressure and electronic configaration of Na & K is ns2,,compounds of Na & K are available most aboundenty in nature so thees two are alkali metal.
Q3. In a π (pi) bond formation, is necessary for one of the below criteria. Choose the appropriate one.
Answer : Option B
Explaination / Solution:
parallel orientataion of p orbitals are necessary for proper overlapping and formation of pie bond.
Q4. Fill up the blank with suitable word in the statement,
" Physical properties are those properties which are measured or observed--------------- changing the identity or the composition of the substance ."
Answer : Option D
Explaination / Solution:
A substance is identified by its composition , hence for measuring physical properties of a substance its identity must be retained , (or should not be changed ) Hence , the given statement ,
" Physical properties are those properties which are measured or observed without changing the identity or composition of the substance."
is correct.
Q5. If we place solid iodine in a closed vessel, after sometime the vessel gets filled up with violet vapour. When equilibrium is attained, the intensity of colour will be
Answer : Option D
Explaination / Solution:
we place solid iodine in a closed vessel, after sometime the vessel gets filled up with violet vapour and the intensity of colour increases with time. After certain time the intensity of colour becomes constant and at this stage equilibrium is attained. Hence solid iodine sublimes to give iodine vapour and the iodine vapour condenses to give solid iodine. The equilibrium can be represented as, I2 (solid) ⇌ I2 (vapour)
Q6. The average Kinetic energy and Thermal energy are proportional to the
Answer : Option C
Explaination / Solution:
The average KE and Thermal energy are proportional to absolute Temperature.
The kinetic energy is the amount of motion in the atoms and molecules of a substance. The moleculess of the gas gain energy as the temperature increases as there is more motion of the molecules. As the temperature decreases the motion lessens until at absolute zero all motion (kinetic energy) stops.
Q7. n the Wurtz reaction method of preparation of alkanes, the stoichiometric coefficient of Sodium is
Answer : Option A
Explaination / Solution:
Wurtz reaction is used for the preparation of alkanes from alkyl halides in the presence of sodium and dry ether.For example: CH3Br + 2Na +BrCH3 ---------> CH3CH3 + 2NaBr
Thus two atoms of Na are used.
Q8. Redox reaction between copper and aqueous solution of silver nitrate happens when copper rod is dipped in silver nitrate solution. What happens in the final stage?
Answer : Option A
Explaination / Solution:
This is due to the formation of Cu2+ ions in the solution illustrated in following ionic reaction:
Cu(S)+2Ag+(aq)--------------˃Cu2+(aq)+2Ag(s)
Here, Cu is oxidized to Cu2+ (means relasing of 2 electrons from Cu to Cu2+ ) and Ag+ is reduced to Ag(s) (means gaining of 2 electrons from 2Ag+ to 2Ag ) and thus, silver converted into solid state and deposited on copper rod.
Q9. It is now recognized that the ‘Modern Periodic Law’ is essentially the consequence of
Answer : Option A
Explaination / Solution:
Modern Periodic Law of element may be defined as the Physical and chemical properties of the elements are periodic functions of their atomic numbers.It means, when the elements are arranged in the order of their increasing atomic numbers, it is observed that the elements of similar properties recur at regular intervals or periodically. As a result of this, the elements fall in certain groups and lead to an arrangement called the modern periodic table of elements. It must be noted that elements are arranged in the periodic table in order of atomic numbers because atomic number is the most fundamental property of an element. The systematic arrangement of elements in modern periodic table according their atomic number helps in justification of isotopes of elements at one place.
Q10. For isothermal reversible free expansion of an ideal gas from the initial volume to the final volume the work done on the gas is
Answer : Option D
Explaination / Solution:
this is workdone by the system in iosothermal process.
