Answer:
6. 7870 kg/m³ (3 s.f.)
7. 33.4 g (3 s.f.)
8. 12600 kg/m³ (3 s.f.)
Explanation:
6. The SI unit for density is kg/m³. Thus convert the mass to Kg and volume to m³ first.
1 kg= 1000g
1m³= 1 ×10⁶ cm³
Mass of iron bar
= 64.2g
= 64.2 ÷1000 kg
= 0.0642 kg
Volume of iron bar
= 8.16 cm³
= 8.16 ÷ 10⁶


Density of iron bar

= 7870 kg/m³ (3 s.f.)
7.

Mass
= 1.16 ×28.8
= 33.408 g
= 33.4 g (3 s.f.)
8. Volume of brick
= 12 cm³

Mass of brick
= 151 g
= 151 ÷ 1000 kg
= 0.151 kg
Density of brick
= mass ÷ volume

(3 s.f.)
Answer:
It is the portion of internal energy that can be transferred from one substance to another.
There will be needed 982.35 mL of solution to obtain 16.1 grams of the salt.There will be needed mL of
Why?
In order to calculate how many milliliters are needed to obtain 16.1 grams of the salt given its concentration, we first need to find its chemical formula which is the following:

Now that we know the chemical formula of the substance, we need to find its molecular mass. We can do it by the following way:

We have that the molecular mass of the substance will be:

Therefore, knowing the molecular mass of the substance, we need to calculate how many mols represents 16.1 grams of the same substance, we can do it by the following way:


Finally, if we need to calculate how many milliliters are needed, we need to use the following formula:


Now, substituting and calculating, we have:

Henc, there will be needed 982.35 mL of solution to obtain 16.1 grams of the salt.
Have a nice day!
I suppose you mean to ask why we can't go through obstacles.
Any atom is surrounded by an electronic cloud. When two atoms get close to each other, the electronic clouds repel each other, preventing them from interpenetrating each other. That same phenomenon, on a larger scale, prevents us from going through matter.