The two elements 11X and 19Y are in the same group because they have the same
valence electrons
ionization energy
number of shell
atomic size
Correct answer is A
No explanation has been provided for this answer.
Hydrogen bonds are formed between molecules containing a hydrogen atom bonded to a
strongly electronegative atom
non-polar species
diatomic element
complex ion
Correct answer is A
No explanation has been provided for this answer.
The crystal layers in graphite are held together by
covalent bond
electrostatic forces
ionic bond
van der Waal's forces
Correct answer is D
The atoms in a given layer are held together by strong covalent linkages, but the forces between the layers are the weak van der waals forces
linear
planar
pyramidal
tetrahedral
Correct answer is D
No explanation has been provided for this answer.
Which of the following substances is mainly responsible for the depletion of the ozone layer?
Oxgyen
Chlorofluorocarbon
Carbon (ll) oxide
Nitrogen (ll) oxide
Correct answer is B
Ozone depletion occurs when chlorofluorocarbons (CFCs) and halons—gases formerly found in aerosol spray cans and refrigerants—are released into the atmosphere