Questions & Answers about Этот стул неудобный, поэтому я сижу на диване.
Because стул is a masculine singular noun, and этот must agree with it.
In Russian, demonstratives like этот change form to match the noun’s:
- gender
- number
- case
So in the nominative singular:
- этот = masculine
- эта = feminine
- это = neuter
Since стул is masculine, you say этот стул.
Неудобный is an adjective meaning uncomfortable or not convenient, and it agrees with стул.
Because стул is:
- masculine
- singular
- nominative
the adjective also takes the masculine singular nominative form:
- неудобный
So:
- этот стул неудобный
is literally this chair is uncomfortable.