In the reactants there is a curvy arrow, what does the direction of the arrow indicate?

Read the sentences below in 1962, i tried to enroll as the first black student at the university of mississippi. the governor of mississippi blocked my entrance which best describes the verbs used in the sentences? o they are past tense verbs, which are often used in narrative essays o they are past tense verbs, which are not often used in narrative essays. o they are future tense verbs, which are often used in narrative essays o they are future tense verbs, which are not often used in narrative essays.

Ahigh energy (high speed) particle (alpha or beta or neutron) are shot at the target;

Anyone know the answer?