Ned is designing an experiment to test which hand sanitizer kills the most e. coli bacteria. in order for ned's results to be valid, what must he do?

the subject is science

So the correct answer is "Test the hand sanitizers on bacterial colonies that are kept in the exact same environmental conditions, such as temperature and light level"

Explanation:

There are several ways to make sure the results of an investigation are valid. First, you and others can try to repeat the experiment. In addition, if it is a controlled experiment, you can make sure you have a control, only one independent variable, at least one dependent variable, and constants.

For Ned's results to be valid, he needs to test the hand sanitizers on bacterial colonies that are kept in the exact same environmental conditions, such as temperature and light level.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.