Chemistry problems
- 1. Which one of the following is not radioactive
Options- A. Astanine
- B. Francium
- C. Tritium
- D. Zirconium Discuss
Correct Answer: Zirconium
- 2. Permanent Hardness of water can be removed by adding
Options- A. Bleaching powder
- B. Chlorine
- C. Wasshing soda
- D. Potassium permanganate Also asked in: AIEEE, Bank Exams, Analyst, Bank Clerk, Bank PO
Correct Answer: Wasshing soda
Explanation:
Hardness can be removed by adding sodium carbonate (washing soda) or by passing the water through an ion-exchange column.
Hardness in water is caused by dissolved magnesium ions and calcium ions. These can get into the water when it comes into contact with limestone and other rocks that contain calcium compounds. This can happen, for example, when rainwater flows over these rocks on its way to a reservoir.
Hardness in water is of two types. They are :
1. Temporary hardness
2. Permanent hardness
1. Temporary hardness:: Temporary hardness is caused by dissolved calcium hydrogen carbonate.
2. Permanent hardness:: Permanent hardness is caused by dissolved calcium sulfate. Unlike temporary hardness, it is not removed by boiling the water.
- 4. Modern periodic table is based on atomic number of the elements. The significance of atomic number was proved by the experiment of ________
Options- A. Moseley's work on X-ray spectra
- B. Bragg's work on X-ray diffraction
- C. Mulliken's oil drop experiment
- D. Discovery of X-ray by Roentgen Discuss
Correct Answer: Moseley's work on X-ray spectra
- 5. The first indication that a stable nucleus can be broken down was afforded by
Options- A. Rutherford
- B. Madam Curie
- C. Soddy
- D. Schmidt Discuss
Correct Answer: Rutherford
- 6. The oxidation number of Cr in K2Cr2O7 is
Options- A. +6
- B. -5
- C. +3
- D. -4 Also asked in: AIEEE, Bank Exams, GATE, Analyst, Bank Clerk, Bank PO
Correct Answer: +6
Explanation:
We will rewrite the formula as an equation.
2K + 2Cr + 7O = 0
The zero comes from there being no overall charge on the compound.
Each oxidation number is represented by the element's symbol.
Since this compound is not a peroxide or superoxide, the oxidation value for O is -2
K being in group 1 has a +1 charge and therefore has an oxidation number of K is +1
Now, by putting known values in we have:
2(+1) + 2(Cr) + 7(-2) = 0
2 + 2Cr -14 = 0
2Cr = +12
Cr = +6.
- 7. Oxidation Number of 'S' in H2SO4 ?
Options- A. +6
- B. +2
- C. -6
- D. -2 Also asked in: AIEEE, Bank Exams, GATE, GRE, Analyst, Bank PO
Correct Answer: +6
Explanation:
In ,
Hydrogen has a charge of +2, with each hydrogen has +1.
Oxygen has a charge of -8, with each oxugen has -2.
Total charge = (2 - 8) = -6
Therefore, the Oxidation number of Sulphur S is '+6' because to make the compound stable.
- 8. How many Covalent Bonds can Nitrogen form
Options- A. 2
- B. 3
- C. 4
- D. 1 Also asked in: AIEEE, Analyst, Bank PO
Correct Answer: 3
Explanation:
Nitrogen ( ) forms Three Covalent Bonds to become stable.
Here the Atmomic Number of Nitrogen is 7. Because there are 2 electrons in the first orbital and 5 in the second and you still have space for 3 more. So it shares, 3 to get the stable octet. Therefore, there are 3 covalent bonds in .
- 9. The Gas used for Artificial Ripening of Green Fruit is
Options- A. Acetone
- B. Di Carbonate
- C. Ethylene
- D. Ethyl Alcohol Also asked in: AIEEE, Bank PO
- Calcium carbide is also used in some countries for artificially ripening fruit. When calcium carbide comes in contact with moisture, it produces acetylene gas, which is quite similar in its effects to the natural ripening agent, ethylene
Correct Answer: Ethylene
Explanation:
Ethylene is used for Artificial Ripening of Green Fruit.
- 10. Neutron was discovered by
Options- A. J.J.Thomson
- B. Chadwick
- C. Rrutherford
- D. Priestley Discuss
Correct Answer: Chadwick
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