Answer:
About 16.1 grams of oxygen gas.
Explanation:
The reaction between magnesium and oxygen can be described by the equation:

24.4 grams of Mg reacted with O₂ to produce 40.5 grams of MgO. We want to determine the mass of O₂ in the chemical change.
Compute using stoichiometry. From the equation, we know that two moles of MgO is produced from every one mole of O₂. Therefore, we can:
- Convert grams of MgO to moles of MgO.
- Moles of MgO to moles of O₂
- And moles of O₂ to grams of O₂.
The molecular weights of MgO and O₂ are 40.31 g/mol and 32.00 g/mol, respectively.
Dimensional analysis:

In conclusion, about 16.1 grams of oxygen gas was reacted.
You will obtain the same result if you compute with the 24.4 grams of Mg instead:

The brownish rock is a sedimentry rock was formed when things like sand, mud, or pebbles get laid down in layers. Eventually the layers are lithified.
The grey rock is a metamorphic rock and was when other rocks are changed because of heat or pressure. Earth movements can cause rocks to be deeply buried or squeezed. As a result, the rocks are heated and put under great pressure. They do not melt, but the minerals they contain are changed chemically, forming metamorphic rocks.
The red dots rock is an igneous rock. Igneous rock forms when hot, molten rock crystallizes and solidifies.
Answer:
The correct answer to the following question will be "4.08 × 10⁻¹⁹ Joule".
Explanation:
Given:
Wavelength, λ = 486.0 nm
As we know,

On putting the estimated values, we get
⇒ 
⇒ 
∴ 1 ev = 1.6 × 10⁻¹⁹ J
Now,
Energy, 
⇒ 
Yes, it would be considered as physical change.
This is mind numbing, but I got you.
3NaOH + 1FeCl<em>3</em> = 1Fe(OH)<em>3 </em>+ 3NaCl
3Mg + 2H<em>3</em>(PO)<em>4</em> = 1Mg(PO<em>4</em>)<em>2</em> + 3H<em>2</em>