Answer
The symbols are $H_{0}$ and $H_{1}$.
Work Step by Step
In hypothesis testing, the null hypothesis and alternative hypothesis are represented by standard symbols:
Null hypothesis:
Symbol: $H_0$
Meaning: The statement that there is no effect, no difference, or no relationship. It’s the hypothesis we assume to be true until evidence suggests otherwise.
Alternative hypothesis:
Symbol:$H_1$
Meaning: The statement that there there is an effect, a difference, or a relationship. It represents what you are trying to provide evidence for.