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- Question
Sodium carbonate crystal lose water molecules this property is called
Options- A. hygroscopy
- B. deliquescence
- C. efflorescence
- D. None of these
- Correct Answer
- efflorescence
- 1. Which one of the following substances does not have a melting point
Options- A. bromine
- B. sodium chloride
- C. mercury
- D. glass Discuss
- 2. Which one of the following mixture is homogeneous
Options- A. starch and sugar
- B. methanol and water
- C. graphite and charcoal
- D. calcium carbonate and calcium bicarbonate Discuss
- 3. The discovery of neutron became very late because
Options- A. it is present in nucleus
- B. it is a fundamental particle
- C. it does not move
- D. it does not carry any charge Discuss
- 4. SI unit of equivalent conductance
Options- A. ohm/cm
- B. Siemens m2/equivalent
- C. Siemens/equivalent
- D. mho/cm Discuss
- 5. A mixture of sand and naphthalene can be separated by
Options- A. Fractional distillation
- B. Sublimation
- C. Chromatography
- D. Any of them Discuss
- 6. The absolute value of charge on electron was determined by
Options- A. J.J.Thomson
- B. R.A. Millikan
- C. Rutherford
- D. Chadwick Discuss
- 7. Which one of the following elements is essential for construction is nuclear reactors
Options- A. Cobalt
- B. Nickel
- C. Zirconium
- D. Tungsten Discuss
- 8. An atom has 7 electrons in its M - shell and contains 18 neutrons in its nucleus. What is its mass number
Options- A. 25
- B. 27
- C. 35
- D. 43 Discuss
- 9. How many electrons are there in Na+
Options- A. 1
- B. 10
- C. 11
- D. 12 Discuss
- 10. ' Misch metal ' is widely used in manufacture of which of the following
Options- A. Material of car brake
- B. Smoke detectors
- C. Cigarette lighters
- D. Emergency lights Discuss
Chemistry problems
Search Results
Correct Answer: glass
Correct Answer: methanol and water
Correct Answer: it does not carry any charge
Correct Answer: Siemens m2/equivalent
Correct Answer: Sublimation
Correct Answer: R.A. Millikan
Correct Answer: Zirconium
Correct Answer: 35
Explanation:
According to Bohr model, Each shell can occupy 2 electrons in their orbits where n=1,2,3.. for K,L,M,..
The atom has 2 electrons in k, 8 electrons in L and 7 electrons in M = 2 + 8 + 7 = 17
And given that its nucleus has 18 neutrons
=> its mass number = number of (electrons + neutrons ) = 17 + 18 = 35
Correct Answer: 10
Correct Answer: Cigarette lighters
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