Question 11
Christy wants to find out if the birds that visit the bird feeders in her backyard would rather build nests in birdhouses or in trees. She puts a birdhouse next to the feeder containing sunflower seeds and hangs a feeder containing cracked corn from a tree. She observes the birds' nesting activities over the next two weeks and records her observations. Which of the following would improve Christy's investigation?

A) setting up a third bird feeder containing fruit near a bird bath

B) putting the same kind of food in both feeders

C) setting the feeders up closer to each other

D) putting more food in both bird feeders

B

Explanation:

because the birds might choose the house based on the food.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.

the glands which are associated with each description is given below: