Covalent for the first one
<span>The answer is D)<em> </em>are compounds that have the same number and types of atoms but are arranged differently.
Source: <em>just took the test :)</em></span>
When the block of iron is placed in water the volume of water that is displaced is 27.0 cm³
<u><em> calculation</em></u>
The volume water that is displaced is equal to volume of block of the iron
volume of block of iron = length x width x height
length= 3 cm
width = 3 cm
height = 3 cm
volume is therefore = 3 cm x 3 cm x 3 cm = 27 cm³ therefore the volume displaced = 27 cm³ since the volume of water displaced is equal to volume of block.
Boyle's law of ideal gas: This law states that the volume of a gas is inversely proportional to its pressure at a constant temperature. Acc to this law we can write the relation of pressure and volume as:
![PV=Constant](https://tex.z-dn.net/?f=%20PV%3DConstant%20)
That means:
![P_{1}V_{1}=P_{2}V_{2}](https://tex.z-dn.net/?f=%20P_%7B1%7DV_%7B1%7D%3DP_%7B2%7DV_%7B2%7D%20)
From that equation we can calculate Volume of gas at a certain pressure:
P₁=Initial pressure
V₁=Initial volume
P₂=Final pressure
V₂= Final volume
Here P₁, initial pressure is given as 85.0 kPa
V₁, initial volume is given as 525 mL
P₂, final pressure is 65.0 kPa
![P_{1}V_{1}=P_{2}V_{2}](https://tex.z-dn.net/?f=%20P_%7B1%7DV_%7B1%7D%3DP_%7B2%7DV_%7B2%7D%20)
so,
V_{2}=85\times 525\div 65
=686 mL
Volume of gas will be 686 mL.
In magnet I believe nickle is used most often