Astudent makes several observations about a piece of iron. which observation describes a chemical property of the iron? a. its mass is 52 grams. b. its density is 7.9 grams/centimeter3. c. it rusts when exposed to air. d. it conducts electricity. 

The correct answer is option C.

Explanation:

Chemical property of the substance is a property which is observed in a chemical reaction during which identity or composition of the substance changes.

Iron when exposed to air ,react with atmospheric oxygen to from ferric oxide which is a reddish brown in color.Also termed as Rust.

Hence, the correct answer is option C.

The correct answer is option C.

Explanation:

Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition identity of the substance gets changed.

For Example: reactivity , toxicity etc.

Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: State, density etc.

The chemical property observed by the the student is that iron rusts when exposed to air. The oxygen present in the air reacts with iron to form reddish brown compound named rust.

Here, iron's reactivity is observed which is a chemical property of the iron.

Where mass ,  density and being a electricity conductor are physical properties.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

they are made of gases.

they have a spherical shape.

they make energy through fusion.