Which is true in a covalent bond?
question 9 options:

the bond forms between ions.

the bond forms when electrons are shared.

the bond holds atoms weakly.

the bond is caused by van der waals forces.

The correct option is: The bond forms when electrons are shared.

Explanation:

Covalent bonds are bonds between nonmetal compounds, where electrons are shared until they reach the octet. Example:

CO2 (carbon dioxide), NH3 (ammonia), H20 (water).

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.