Answer: 2. cannot be an element.
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: methane 

Thus as it can be decomposed into its constituent elements, it is a compound.
Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present.
Thus methane cannot be an element.
Answer:
5 mL
Explanation:
Given data:
mass of ring = 107 g
volume of water = 10 mL
increase in volume = 15 mL
How much water displace = ?
Solution:
V (ring) = V (water + ring) - V (water)
V (ring) = 15 mL - 10 mL
V (ring) = 5 mL
when the ring is put into cylinder, volume is increased by 15 mL. The volume of water was 10 mL so water is displaced by 5 mL and the volume 5mL is the voulme of ring.
Answer:
Sorry mate! I can't understand this language...
Answer:
58.0 g of MgO
Explanation:
in a perfect world, 70 g, however we don't live in a perfect world
The equation of reaction
2Mg + O₂ --> 2MgO
first find which element is limiting:
35 g x 1 mol/24.3 g of Mg x 2 mol of MgO/ 2 mole of Mg = 1.44 moles of MgO
35 g x 1 mol/32g of Mg x 2 mol of MgO/ 1 mole of O₂ = 2.1875 moles of MgO
This means Mg is the limiting factor, so you will be using this moles to find grams of MgO
1.44 mols of MgO x 40.3 g of MgO/ 1 mol = 58.0 g of MgO
When you add heat to a solid the particles gain energy and start to vibrate faster and faster.
When you add heat to a liquid the particles are given more energy and move faster and faster expanding the liquid.