Answer:
λ = 1.43 x 10³ meters (radio waves)
Explanation:
c = f·λ => λ = c/f
λ = wavelength = ?
f = frequency = 2.10 x 10¹⁴ Hz = 2.10 x 10¹⁴ cycles/sec
c = speed of light (vacuum) = 3.0 x 10⁸m/sec
λ = c/f = 3.0 x 10⁸m/sec / 2.10 x 10¹⁴sec⁻¹ = 1.43 x 10³ meters (radio waves)
8. A. Density is independent of size (an intensive property).
9. B. The highest density is 1786 g/20cm^3, or 89.3 g/cm^3. The least is 512 g/20cm^3, or 25.6 g/cm^3. Therefore, the difference is 89.3 - 25.6, or 63.7 g/cm^3.
10. C. A bottle filled with air weighs less than one filled with marshmallows, because air is less dense than marshmallows.
11. D. The number represents the number of protons in the nucleus of the atom, as well as the atomic number of the element.
12. C. The number represents the atomic mass of the element, which is determined based on the relative abundance of each form of the element.
Answer:
1. a receptacle in a church for the water used in baptism, typically a freestanding stone structure.
2. A type of writing or text style
Explanation:
There are mutiple definitions of font
Answer : The mass of oxygen formed must be 3.8 grams.
Explanation :
Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
The balanced chemical reaction will be,

According to the law of conservation of mass,
Total mass of reactant side = Total mass of product side
Total mass of
= Total mass of 
As we are given :
The mass of
= 25.3 grams
The mass of
= 23.4 grams
So,



Therefore, the mass of oxygen formed must be 3.8 grams.
combustion is when you burn something in presence e of oxygen and the products will be mainly the CO2 and H2O