Answer: 59 grams
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
Given: mass of hydrogen = 6.6 g
mass of oxygen = 52.4 g
Mass of products = Mass of hydrogen + mass of oxygen = 6.6 +52.4 = 59 g grams
Thus mass or reactant = mass of water
Mass of reactants = mass of products = 59 g
Thus the mass of water initially present was 59 g.
Round off .00042557 to three significant digits is = 0.000426
<h3>What is round of value ?</h3>
- If 5, 6, 7, 8, or 9 come after the number you are rounding, round it up. For instance, 40 is the result of rounding 38 to the nearest ten.
- If the numbers 0, 1, 2, 3, or 4 come after the number, round it down. If 33 is rounded to the nearest ten, it becomes 30.
- To estimate a certain number in a context, rounding is a process. Look at the next digit in the correct position to determine how to round a number; if it is less than 5, round down, and if it is 5 or more, round up.
Given
The digit of 00042557
Three significant digits is 0.000426
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Answer:
4.907 × 10^-19 J
Explanation:
The energy of the lasers in a Blu-ray player can be calculated by using;
E = hf
Where;
E = Energy of laser (J)
h = Planck's constant (6.626 × 10^-34 J/s)
f = frequency (Hz)
However, the frequency must be known first in order to calculate the energy. The frequency can be calculated using the formula:
f = v/λ
Where:
λ = wavelength (4.05x10−7 m.)
v = speed of light (3 × 10^8m/s)
f = frequency (Hz)
f = 3 × 10^8 ÷ 4.05 x 10^−7
f = 0.7407 × 10^(8 + 7)
f = 0.7407 × 10^15
f = 7.407 × 10^14 Hz
Using E = hf
E = 6.626 × 10^-34 × 7.407 × 10^14
E = 49.07 × 10^(-34 + 14)
E = 49.07 × 10^-20
E = 4.907 × 10^-19 J
Majority of an atoms mass comes for protons and neutrons which makes up the nucleus.
The person may probably die