Select the correct statement or statements about compounds and molecules:

chose all that are correct

1) compounds don’t act like their elements; compounds act like a different substance.

2) a molecule can be made of one type of element or a mixture of elements.

3) a molecule is two or more atoms bonded together.

4) a compound is made of just one type of element.

1) and 3)

Step-by-step explanation:

Step-by-step explanation:

A compound is a molecule which is made of atoms from different elements.

Compounds are useful beacuse they don't actually act like their elements. For example, if you think about , you observe that it's a compund of 2 atoms of hydrogen and 1 atom of oxygen, but the compund doesn't act like hydrogen or oxygen, it's water. Therefore, the first choice is correct.

Now, as we said before, a molecule is form by atoms, specifically by two or more, because a single atom cannot form a molecule, it would be just an atom by itself. Therefore, the third choice is correct.

So, the right choices are 1 and 3.

answer: 25 is the correct answer

step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.