Chemistry - Online Test
Q1. Surface tension decreases as the temperature is raised because
Answer : Option D
Explaination / Solution:
Surface tension decreases as the temperature is raised because Increase in temperature increases the kinetic energy of the molecules and effectiveness of intermolecular attraction decreases.
Q2. The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali
Answer : Option C
Explaination / Solution:
The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali are called Buffer Solutions. Buffer solutions of known pH can be prepared from the knowledge of pKa of the acid or pK b of base and by controlling the ratio of the salt and acid or salt and base. A mixture of acetic acid and sodium acetate acts as buffer solution around pH 4.75 and a mixture of ammonium chloride and ammonium hydroxide acts as a buffer around pH 9.25.X`
Q3. Enzymes are used in the reaction as they are
Answer : Option A
Explaination / Solution:
Enzymes are bio catalyst
Q4. The reaction in Q No.26,phenols are
Answer : Option B
Explaination / Solution:
Phenols are bronsted acids (proton donor). –OH is polar.
Q5. Which of the following method is not a synthetic method for production of Benzene?
Answer : Option A
Explaination / Solution:
Since isolation of benzene from coal tar involves separation of benzene from other components through a physical operation "fractional distillation" , it is NOT a synthetic method for production of benzene.
Q6. Amalgam of mercury with sodium is an example of
Answer : Option B
Explaination / Solution:
Solute is mercury( liquid) and solvent is sodium.
Q7. Which among the following is miscible in each other?
Answer : Option A
Explaination / Solution:
Methanol and Water both are Polar. There is intermolecular Hydrogen Bonding interaction.
Q8. The Hofmann elimination proceeds via a(n) __________ pathway.
Answer : Option D
Explaination / Solution:
Hoffmann elimination follows mechanism.
Q9. Assign oxidation number to P in
Answer : Option D
Explaination / Solution:
Oxidation state of P in NaH2PO4 is +5.
Let the oxidation number of P be x. As we already know oxidation number of other atoms so we can calculate that of P too.
Na = +1
H= +1 (+2 for hydrogen molecule)
O = -2
Now calculating oxidation number of P:-
1 +2 + x +(-8) = 0
On solving we get x= +5.
Q10.
Consider the chemical equation ,
----- KOH + ----- H3PO4 → ----- K3PO4 + ----- H2O.
The equation can be balanced by inserting the following in blank spaces
Answer : Option C
Explaination / Solution:
The given equation gets balanced by inserting the coefficients (3 , 1 ,1 ,3 ) in blank spaces from LHS to RHS . Thus, the balanced equation for the given reacion is ,
3KOH + H3PO4 → K3PO4 + 3H2O.
