Chemistry Chapter 4 book 1:

1.     Possible angle between two hydrogen atom in hydrogen atoms bonded framework of HF is

a)     109.5⁰

b)    120⁰

c)     145⁰

d)    180⁰

2.     When the water freezes at 0⁰C , its density decreases due to

a)     Cubic structure of ice

b)    Presence of empty spaces

c)     Change of bond length

d)    Change of the bond angle

3.     Three hydrogen bonds exist between nitrogenous bases in DNA. The bases are

a)     Cytocein and adenine

b)    Adenine and guanine

c)     Cytocein and guanine

d)    Adenine and thiamin

1.b

2.b

3.c