Electropositivity of elements across the periodic table normally
remains constant down the group
Increases across the period
decreases across the period
decreases down the group
Correct answer is C
Electropositivity is known to increase down groups and decrease across periods in the modern periodic table (i.e., electropositivity decreases from left to right and it increases from up to down).
The atom with the electron configuration
1s22s22p63s23p63d104s24p4 is in
period 4, p- block
period 3, p- block
period 4, d- block
period 3, d- block
Correct answer is A
Selenium is a chemical element with the symbol Se and atomic number 34. It is a non-metal
Which of the following statements about atoms of a metal is correct? They
readily accept electrons
are soft
are held together by covalent bond
are held together by a sea of electron cloud
Correct answer is D
Metals are effectively lots of positively charged ions with a cloud/sea of delocalised electrons. This means the electrons are free to move throughout the metal, and is also why metals can conduct electricity as the electrons can move. The more delocalised electrons a metal has, the stronger it will be held together.
An oxide has the following properties. It
I. is a white powder
II. reacts with HCI.
III. reacts with NaOH
IV. is insoluble in water
The oxide is
alkaline
amphoteric
acidic
neutral
Correct answer is B
An amphoteric oxide is an oxide that can act as either an acid or base in a reaction to produce a salt and water.
The electron configuration of carbon atom in its excited state is
1s22s22px22py0
1s22s22px12py1
1s22s12px12py12pz1
1s12s22px12py1
Correct answer is C
- So any electron configuration in which the last electron (again, the valence electron) is in a higher energy orbital, this element is said to be in an excited state.
- When a carbon atom becomes excited by absorbing energy, one of its 2s electrons is promoted into the 2p sublevel.