An atom had a mass of 43 and it also has has 21 electrons

scandium. if you look up the number of electrons thats the periodic number and it gives you the answer

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.