What does the below rebus riddle means?

What occurs twice in a week, once in a year but never in a day?

I can write cow in 13 letters.

Can You?

Replace the question mark with the number below given a simple math problem.

Rose, Lily and Jasmine decided to buy flowers for their moms on Mother's Day. One of them bought lilies, the other roses, and the third one jasmines.
'It's funny!' said the girl with roses, 'we bought roses, jasmines and lilies, but none of us bought the flowers matching her name'.
'You're right!', said Lily.
What kind of flowers did each of the girls buy?

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

Can you replace the question mark with the correct number in the below table sequence?

What number do you get when you multiply all of the numbers on a telephone's number pad?

Spot what is wrong here in below Picture?

A maths symbol is hidden in the below Bar Graph. Can you decipher it?