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- Question
Permanent Hardness of water can be removed by adding
Options- A. Bleaching powder
- B. Chlorine
- C. Wasshing soda
- D. Potassium permanganate
- Correct Answer
- Wasshing soda
ExplanationHardness 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. - 1. Which one of the following is not radioactive
Options- A. Astanine
- B. Francium
- C. Tritium
- D. Zirconium Discuss
- 2. A device used for the measurement of radioactivity is
Options- A. mass spectrometer
- B. cyclotron
- C. nuclear reactor
- D. G.M.counter Discuss
- 3. The particle with 13 protons and 10 electrons is
Options- A. Al -atom
- B. Al3+ ion
- C. nitrogen isotope
- D. None of these Discuss
- 4. Which of the following carbon compounds is used as a fire- extinguisher?
Options- A. Carbon disulphide
- B. Chloroform
- C. Carbon tetrachloride
- D. Methyl ene chloride Discuss
- 5. Van der Waal's equation explains the behaviour of _____
Options- A. Ideal gases
- B. Real gases
- C. Mixture of gases
- D. Diatomic gases Discuss
- 6. The Most Important Ore of Aluminium is
Options- A. Calamine
- B. Monazite
- C. Magnetite
- D. Bauxite Discuss
- 7. 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
- 8. 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
- 9. The oxidation number of Cr in K2Cr2O7 is
Options- A. +6
- B. -5
- C. +3
- D. -4 Discuss
- 10. Oxidation Number of 'S' in H2SO4 ?
Options- A. +6
- B. +2
- C. -6
- D. -2 Discuss
Chemistry problems
Search Results
Correct Answer: Zirconium
Correct Answer: G.M.counter
Correct Answer: Al3+ ion
Correct Answer: Carbon tetrachloride
Explanation:
Vapour of carbon tetra chloride is non-inflammable and is heavier than air. Hence it is used as a fire extinguisher under the trade name of pyrene.
Correct Answer: Real gases
Correct Answer: Bauxite
Correct Answer: Moseley's work on X-ray spectra
Correct Answer: Rutherford
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.
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.
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