Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

What work can one never finish?

I am the largest in my family of fifty.
The youngest of our family lives separately from the rest of the family and so do I.
I am regarded as harsh and tough.
I am so large, you cut me in two equal halves,
each half would still be larger than the second largest member of the family.
Who am I?

How many runs at maximum can a batsman score in a normal one-day match? Consider the fact that the conditions are ideal and there are no No Balls, no Wide Balls and no Extras in that match.

10+10 and 11+11 can give you the same answer.

Explain how?

What has one letter and starts with an E?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

You have a basket containing ten apples. You have ten friends, who each desire an apple. You give each of your friends one apple.
Now all your friends have one apple each, yet there is an apple remaining in the basket.
How?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?