You opened and were in the minimum range to open the bidding. With your rebid you should support your partner at the 2 level. This shows you have 4 cards in ♥ and 12-14 points.

3) What's your rebid?

Never deny your major. Your partner could still hold 4 cards in Spades so a Spade fit is still possible.

If you bid 1NT, you deny 4 cards in the majors (you didn’t bid 1♠ or support Hearts).

By bidding 1♠ you show 12-17 points and 4 cards in Spades.

Note that partner's 1♥ bid could be just 4 cards, so you need 4 cards too in order to support with 2♥.

4) What's your rebid?

You opened and were in the minimum range to open the bidding. You should rebid 1NT, showing you have 12-14 points, a balanced hand, and you don’t have 4 cards support in ♠.

2♥ would be a reverse bid, showing 16+ points and an unbalanced hand.

Note that partner's 1♠ normally denies 4 cards in ♥. But if partner has 5 cards in ♠ and 4 cards in ♥, they can still bid ♥ on the next bid and you'll find the 4-4 possible Heart fit.

5) What's your rebid?

You opened the bidding and are in the minimum points range. You need to rebid your suit at the 2 level, showing you have 6 cards in ♥ and 12-14 points.

Note that partner's 1♠ response could mean 4 cards in ♠ - to support it you also need 4 cards in ♠.

6) What's your rebid?

You opened the bidding and are in the minimum points range. You need to rebid your suit at the 3 level, showing you have 6 cards in ♥ and 15-17 points.

Note that partner's 1♠ response could mean 4 cards in ♠ - to support it you also need 4 cards in ♠.

7) What's your rebid?

You opened the bidding and are in the minimum points range. You need to rebid your 2nd suit at the 2 level (2♣ here), showing you have 5 cards in ♥, 4 cards in ♣, and 12-17 points.

If bidding continues, you'll most likely pass next, to show you have minimum (unless partner makes a forcing bid).

8) What's your rebid?

10) What's your rebid?

Correct Answer: 2♥

You opened the bidding and are in the maximum points range. You need to bid 2♥; a reverse bid, showing 17-21 points (or 16 with good hands) an unbalanced hand (normally at least 5 cards in ♣ and 4 cards in ♥), and is at least 1 round forcing.

A reverse bid is a new suit, at the 2 level, which is higher by rank than the suit you bid at the 1 level.