CBSE 12TH CHEMISTRY - Online Test
Q1. One of the following rubbers is used in making oil seals, tank lining, etc.
Answer : Option C
Explaination / Solution:
Buna N is used in making oil seals , tank linings.
Q2. The thermal stability of hydrides of group 16 elements decreases in the order
Answer : Option A
Explaination / Solution:
As we move down the group bond length increases and bond enthalpy for the dissociation of H-E bond decreases. Due to decrease in enthalpy the thermal stability of hydrides decreases down the group.
Q3. ZnCO3(s)−→ΔZnO(s) + CO2 ;The reaction shows the process of
Answer : Option C
Explaination / Solution:
Carbonate ore is heated to a high temperature in the absence of air is calcination
Q4. Which of the following metals have only one oxidation state?
Answer : Option B
Explaination / Solution:
Al is not a d block element hence it shows only one oxidation state. While rest all others are d block elements which shows variable oxidation state.
Q5. One of the following is used for the separation and purification of aldehydes
Answer : Option A
Explaination / Solution:
NaHSO3 is used for purification of aldehydes.
Q6. Hormones relating to birth control are
Answer : Option C
Explaination / Solution:
Hormones related to birth control are Estrogen and progesterone.
Q7. Which is not true about a ligand?
Answer : Option B
Explaination / Solution:
Multidentate ligand always act as chelating Ligand
Q8. A secondary cell after use ________ recharged by passing current through it in the ________ so that it can/can’t be used again.
Answer : Option B
Explaination / Solution:
Secondary cell can be recharged and reused.
Q9. 
In the reaction Pent – 2 – ene. 2 – Bromopentane. Pent – 1 – ene 2 – Bromopentane on heating with alcoholic KOH, forms two compounds: Pent – 1 – ene and Pent – 2 – ene. Which one of the following statements is true
In the reaction Pent – 2 – ene. 2 – Bromopentane. Pent – 1 – ene 2 – Bromopentane on heating with alcoholic KOH, forms two compounds: Pent – 1 – ene and Pent – 2 – ene. Which one of the following statements is true
Answer : Option D
Explaination / Solution:
Pent-2-ene is major product as ore substituted alkene is formed in major quantity according to zaitsev rule.
Q10. The radioactive isotope used in determining the age of organic substances is
Answer : Option A
Explaination / Solution:
The ratio of Carbon -12 to Carbon-14 at the moment of death is the same as every other living thing., but Carbon-14 decays and is not replaced. The carbon-14 decays with its half-life of 5770 years., while the amount of Carbon-12 remains constant in the sample. By looking at the ratio of Carbon-12 to Carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing fairly precisely.
