An element X with relative atomic mass 16.2 contains two isotopes \(^{16}_{8}\)X with relative abundance of 90% and \(^{m}_{8}\)X with relative abundance of 10%. The value of m is
- A. 16
- B. 18
- C. 12
- D. 14
Four elements W, X, Y and Z have atomic number 2,6,16 and 20 respectively. Which of these elements is a metal?
- A. X
- B. W
- C. Z
- D. Y
Millikan’s contributions to the development of atomic theory is the determination of
- A. charge on electron
- B. positive rays
- C. charge to mass ratio
- D. cathode rays
An oxide XO\(_2\) has a vapour density of 32. What is the atomic mass of X?
- A. 32
- B. 20
- C. 14
- D. 12
Cancerous growths are cured by exposure to
- A. ฮณ - rays
- B. ฮฒ - rays
- C. ฮฑ - rays
- D. infrared rays
A particle that contains 9 protons, 10 neutrons and 10 electrons is a
- A. negative ion
- B. positive ion
- C. neutral atom of non-metal
- D. neutral atom of a metal
What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen?
[H = 1, O = 16]
- A. 36.0g
- B. 8.0g
- C. 72.0g
- D. 16.0g
25cm\(^3\) of a gas X contains Z molecules at 15\(^0\)C and 75 mmHg. How many molecules will 25cm\(^3\) of another gas Y contain at the same temperature and pressure?
- A. 2 Y
- B. 2 Z
- C. Z
- D. Y