Zinc + Hydrochloric Acid → Zinc Chloride and Hydrogen Gas Zn + 2HCl → ZnCl2 + H2

Explain why it is necessary to place a "2" in front of HCl in the reactants in the chemical equation. Use "evidence" and "scientific" reasoning to support your answer.

This is because you need the same amount of atoms on each side and when you go to the reaction side you see that by adding the coefficient in from the H, 2, the hydrogen and chlorine react to make HCI :))

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).