CIT Apeal of income tax

yea you have to pay 20% of liability of demand 

Type of Income is irrelevant.In general 20% had to be paid.

Stay petition has to be filed simultaneously for rest of demand. 

yes but not required at the time of filing appeal, it can be later on paid when ao directs

In my opinion the condition on 20% of tax to be paid is only directive and not compulsive regarding  further processing of the case.

Let us say in a case where the assessed has become a bankrupt, he may not be in position to pay such amount at that moment.

In such case, the case may not be  delayed  for hearing showing such cause.

This provision may be brought to safeguard the  Interest of the Revenue.But still it may vary from case to case depending upon the situation.

Before filing the appeal, the taxpayer should pay the tax determined as per the return of income filed by him.

If no return of income is filed, the taxpayer should pay tax equal to the amount of advance tax payable by him. However, on application made by the taxpayer, the Commissioner of Income-tax (Appeal) may exempt the taxpayer from payment of tax before filing the appeal

No , it is not fixed that 20% is mandatorily required to be paid .It depend upon the case to case basis .