Answer: 2
Explanation: Greenhouse gases are very important in keeping our planet just right. If we have too many Greenhouse gases it would be too hot, but we can't eliminate all of them or it will be too cold
The catalyst (4) decreases the activation energy required for a reaction, by holding reactants in place
The overall charge of an atom is positive if the number of electrons is less than the number of protons. Electrons are negatively charged particles while protons are positively charged particles. If there are less electrons as compared to the number of protons in an atom, then naturally the overall charge of the atom would be positive since there are excess protons. Another case would be that the overall charge of an atom is negative if the number of electrons is greater than the number of protons. An atom having more electrons than the number of the protons present would lead to a negative value of the charge since there are excess electrons.
Explanation:
It is the heat required to change a gram of substance from a liquid to a gas.