CBSE 12TH CHEMISTRY - Online Test
Q1. The oxidation number of Fe in K4[Fe(CN)6] is
Answer : Option B
Explaination / Solution:
CN has charge of –1 charge.
Q2. Norethindrone is a
Answer : Option C
Explaination / Solution:
Norethindrone is synthetic infertility drug.
Q3. standard hydrogen electrode operated under standard conditions of 1 atm H2 pressure, 25°C, and pH = 0 has a cell potential of
Answer : Option A
Explaination / Solution:
Standard electrode potential of hydrogen electrode is taken as 0V.
Q4. For the same alkyl group, an alkyl bromide has a higher boiling point than alkyl fluoride because,
Answer : Option C
Explaination / Solution:
Vanderwall forces increases with increase in molecular mass and boiling point increases with vanderwall forces..
The main factor affecting the boiling point is the molecular weight, as can be pictured from the noble gases boiling point in the periodic table (the noble gases are those which have the weakest interactions due to their complete outer shell). But note that if you want to consider all the effects altogether, you must use Kelvins instead of Celsius. So going from 44°C to 88°C is not twice as much but a mere 14% increase.
The other factor affecting boiling point is the nature and strength of intermolecular interactions, usually in the order ionic > hydrogen bond > dipole-dipole > Van der Waals.
In the comparison of RF vs RBr boiling point, molecular weight is definitely in favor of higher boiling points for RBr, at least for small molecules. It is true that the C-F bond is much more ionized than C-Br so it will create stronger dipole-dipole interactions but not sufficiently to compensate for the effect of the mass increase.
Q5. The number of asymmetric carbon atom(s) in below figure is are
Answer : Option A
Explaination / Solution:
Only 1 asymmetric center.
Q6. Molecularity of a reaction
Answer : Option A
Explaination / Solution:
Molecularity means minimum no. of atoms molecules or ions which undergo collision for conversion of reactant to Product. So it is a whole no. Cannot be fractional or negative.
Q7. Metals like silver and copper can be obtained in the colloidal state by
Answer : Option D
Explaination / Solution:
Metal sols are prepared only by Bredig’s Arc method.
Q8. The following reaction takes place in the presence of
Answer : Option A
Explaination / Solution:
-NO2 group is reduced to –NH2 using H2/Pd.
Q9. C6H5OCH2CH3 is called
Answer : Option D
Explaination / Solution:
C6H5OCH2CH3 is ethyl phenyl ether or phenetole is an organic compound that is an ether. Ethyl phenyl ether has the same properties as some other ethers, such as volatility, explosive vapors, and the ability to form peroxides.
IUPAC name : Ethoxybenzene
Other names : Phenetole, Ethyl Phenyl Ether
Q10. Molarity of the solution is
Answer : Option B
Explaination / Solution:
