In the periodic table all elements within the same group have the same
number of neutrons
number of valence electrons
number of isotopes
atomic number
Correct answer is B
The elements in the same group in the periodic table has the same number of electrons in the outer shell. That means, they have the same number of valence electrons.
The element with electron configuration 1s\(^2\) 2s\(^2\) 2p\(^6\) 3s\(^2\) 3p\(^1\) belongs to
s-block period 3, group 1
p-block, period 3, group 2
s-block, period 3, group 3
p-block, period 3, group 3
Correct answer is D
1s\(^2\) 2s\(^2\) 2p\(^6\) 3s\(^2\) 3p\(^1\) = 2, 8, 3.
The element is in period 3 and group 3.
Which of the following arrangements represents the correct order of electronic energy level?
1s 2p 2s 3p 3s 3d 4s
1s 2s 2p 3s 3p 3d 4s
1s 2s 2p 3s 3p 4s 3d
1s 2s 3s 2p 3p 4s 3d
Correct answer is C
The correct order of electronic energy level is OPTION C according to the Aufbau principle.
Which of the following statements is correct?
Atomic size decreases down the group
Atomic size increases across the period
Anions are smaller than the parent atom
Cations are smaller than the parent atom
Correct answer is D
A cation is a positively charged ion. This means electron is given out by a cation, hence the cation is smaller than the parent atom.
An atom of an element X gains two electrons. The symbol of the ion formed is
X +
X 2+
X 2-
X -
Correct answer is C
X gained two electrons. X = 2-.
The ion formed is X\(^{2-}\).