1. The mass number of an atom is equal to the sum of protons and neutrons in the nucleus. A helium atom has 2 protons and 2 neutrons. What is the mass number of this atom?
fon in ach atom of the element All?

Afarmer who is grown corn for the past five years notices in the sixth year that the his harvest is significantly smaller, despite an increase in labor on the farm. the following year, the harvest continue to decline. which of the following explanations most plausibly accounts for the reduction in corn yield? a) soil degradation b) desalinization c) better irrigationd) terracing