Question

1. why can scientists ignore the forces of attraction between particles in a gas under ordinary conditions?

they are too weak to have an effect at the temperatures at which most gases exist.
they do not exist for particles that have kinetic energy.
they are too weak to have an effect at great distances between gas particles.

Explanation:

In gases under ordinary conditions, gas particles have high kinetic energy. The forces of attraction between gas particles are very weak. At the temperatures where most gases exist (relatively high compared to the condensation point), the kinetic energy of gas particles overcomes the weak intermolecular forces. Also, the distances between gas particles are large. But the key reason scientists can ignore the forces of attraction is that at the temperatures at which most gases exist, the forces are too weak to have an effect. The option "They are too weak to have an effect at the temperatures at which most gases exist" correctly explains this.

Answer:

They are too weak to have an effect at the temperatures at which most gases exist.