Answer:
0.88mol
Explanation:
The number of moles, n, contained in a substance can be calculated using the formula;
Moles (n) = mass (m) ÷ molar mass (MM)
Molar mass of Magnesium oxide (MgO) = 24 + 16
= 40g/mol
According to the question, Mass of MgO = 35grams
Mole = 35/40
Mole = 0.875
Mole = 0.88mol
Answer:
Frequency = 0.005× 10¹⁷ s⁻¹
E = 0.03 × 10⁻²⁰KJ
Explanation:
Given data:
Wavelength of light = 630.0 nm (630 × 10⁻⁹ m)
Frequency of light = ?
Energy in joule = ?
Solution:
speed of light = wavelength × frequency
Frequency = speed of light / wavelength
Frequency = 3 × 10⁸ m/s / 630 × 10⁻⁹ m
Frequency = 0.005× 10¹⁷ s⁻¹
Energy:
E = h. f
E = 6.63× 10⁻³⁴ Kg. m²/s × 0.005× 10¹⁷ s⁻¹
E = 0.03 × 10⁻¹⁷ j
E = 0.03 × 10⁻¹⁷ j×1 kj /1000 j
E = 0.03 × 10⁻²⁰KJ
