Answer: heat
Other indicators: color change, odor, gas, temperature change.
Answer:
(iv) (A) is false, but (R) is true.
Explanation:
It is not true that carbon has a strong tendency to either lose or gain electrons to attain noble gas configuration. Carbon is a member of group 14, it is the first member of the group and carbon is purely a non metal. Only metals metals can loose electrons to attain the noble gas configuration. Moreover, carbon does not participate in ionic bonding so it does not gain electrons to attain the noble gas configuration.
However, carbon participates in covalent bonding where it is covalently bonded to four other chemical species using its four outermost electrons. Carbon forms covalent bonds in which four electrons are shared with other chemical species.
My guess is b for the question
Answer:
The mass of Na₂O that can be produced by the chemical reaction of 4.0 grams of sodium with excess oxygen in the reaction is 5.39 grams.
Explanation:
You know the balanced reaction:
4 NA + O₂ ⟶ 2 Na₂O
By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) react and are produced:
- Na: 4 moles
- O₂: 1 mole
- Na₂O: 2 moles
Being:
the molar mass of the compounds participating in the reaction is:
- Na: 23 g/mole
- O₂: 2*16 g/mole= 32 g/mole
- Na₂O: 2*23 g/mole +16 g/mole= 62 g/mole
Then by stoichiometry of the reaction they react and are produced:
- Na: 4 moles* 23 g/mole= 92 g
- O₂: 1 mole*32 g/mole= 32 g
- Na₂O: 2 moles* 62 g/mole= 124 g
Then you can apply the following rule of three: if 92 grams of Na produce 124 grams of Na₂O, 4 grams of Na, how much mass of Na₂O does it produce?

mass of Na₂O=5.39 g
<em><u>The mass of Na₂O that can be produced by the chemical reaction of 4.0 grams of sodium with excess oxygen in the reaction is 5.39 grams.</u></em>