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Is this a valid case in blockchain?
if yes whether the reward for t1 is shared and if not, which block will be invalidated or why not everyone will prefer to solve the block with a single transaction 
Is this a valid scenario in blockchain?
Answers
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You didn’t specify, so I’ll answer in terms of the btc blockchain:
When two valid blocks with the same blockheight are found, only one will be accepted into what will become the longest valid chain. The other will be discarded, it is what is called an orphan block.
Usually, the block that propagates through the network first and fastest is the one that will be accepted into the longest chain. The number or nature of the transactions will not affect which block is accepted (so long as all of the transactions are valid). The miner that found the orphaned block receives no part of the reward, since the orphaned block is dropped from the chain.
Is there any scenario where reward is shared among two or more miners? – wadhwa94 – 2018-02-23T14:50:11.917
1@wadhwa94 no, only one miner/pool is rewarded per block. If multiple individual miners contributed hashrate to the winning pool, then those individuals would be paid out by the pool’s operator, according to the pool’s rules. This payout would be initiated by the pool’s operator, it would not be in the coinbase transaction itself. – chytrik – 2018-02-23T17:20:36.297