43
Which of the following changes is characteristic of an alpha-particle emission?
- A. the nucleus loses two protons and two neutrons
- B. a proton combines with an electron giving off heat
- C. the nucleus splits into two equal parts
- D. four neutrons are lost
44
Which of the following sets of elements are arranged in order of decreasing atomic size in the Periodic Table?
- A. 6C, 4Be, 7N,8 O
- B. 4Be,6 C,7 N,8 O
- C. 8O, 7 N, 6C, 4Be
- D. 7N, 8O, 6C,4Be
45
What is the mass number of an element having 20 neutrons, 15 protons and 15 electrons?
- A. 15
- B. 30
- C. 35
- D. 50
46
The electronic configuration of an element X is 1s22s 22s63p 2 3p4. It can be deduced that X
- A. Belongs to group 6 of the Periodic Table
- B. Belongs to group IV of the Periodic Table
- C. has 3 unpaired electrons in its atom
- D. has relative molecular mass of 16