The unknown substance : Lead
<h3>Further explanation</h3>
Given
Density of element
mass of unknown substance = 40 g
volume = 3.5 cm³
Required
The density of unknown substance
Solution
Density is the ratio of mass per unit volume
The unit of density can be expressed in g/cm³ or kg/m³
Density formula:

Input the value to find the density of an unknown substance :
ρ = 40 g : 3.5 cm³
ρ = 11.43 g/cm³
If we look at the table, the substance which has a density of 11.43 is Lead
Answer:
\large \boxed{5}
Explanation:
Molecules of NH₄OH do not exist.
If they did, however, here is how you might answer.
Total H atoms = 39 H
-7H₂O =<u> 14 </u>
H atoms available = 25 H
Each "molecule" of NH₄OH contains five H atoms.

Boyle's law gives the relationship between pressure and volume of gas. It states that for a fixed amount of gas at constant temperature, pressure is inversely proportional to volume of gas.
PV = k
where P - pressure, V - volume and k - constant
P1V1 = P2V2
where parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation.
substituting the values in the equation
0.947 atm x 150.0 mL = 0.987 atm x V
V = 144 mL
therefore new volume is 144 mL
Answer:Family, Genus, Species.
Explanation:
The answer is group 1A.
In the ionic compound formula X₂SO₄, SO₄ has a -2 charge. Hence to balance this -2 charge of SO₄, X must have a +1 charge.
Group 1A elements form X⁺ type of ions because they are metals. So, they have the tendency to lose electrons.
Hence, X must belong to the 1A group.
Ionic Compounds-
- Ionic compounds are formed by the electrostatic attraction between the anions and the cations.
- Cations are positively charged ions that are formed due to the loss of electrons.
- And the anions are negatively charged ions that are formed due to the gain of electrons.
- Due to this, they have opposite charges and form bonds known as Ionic Bond.
To learn more about Ionic compounds, visit: brainly.com/question/9167977
#SPJ4