Question

9 multiple choice 1 point which of these is an element? shaving cream milk iron steel 10 numeric 1 point how many significant figures are in 0.400 kg? answer 11 multiple choice 1 point which of these contains only 1 type of molecule? element homogeneous mixture heterogeneous mixture compound

Explanation:

Question 9

An element is a pure substance made of only one type of atom. Shaving cream and milk are mixtures. Steel is an alloy (a mixture of iron and other elements). Iron is an element from the periodic - table.

Step1: Recall significant - figure rules

Non - zero digits are always significant. Zeros between non - zero digits are significant. Trailing zeros after a decimal point are significant.

Step2: Analyze 0.400

The digit 4 is significant. The two trailing zeros after the decimal point are also significant.

An element consists of only one type of atom, which can be considered as one type of molecule (in the case of monoatomic elements like noble gases or when considering the elemental form). A homogeneous mixture has a uniform composition but can contain multiple types of molecules. A heterogeneous mixture has a non - uniform composition and multiple types of substances. A compound is made of two or more different types of atoms chemically combined, so it has one type of molecule but is a more specific case compared to an element.

Answer:

C. iron

Question 10