So,
With addition, we the last digit we keep will be the one which is known for both individual values.
We know 2.13 to the hundredths, but we only know 1 to the ones. Therefore, we will round off in the ones place.
2.13 + 1 = 3.13 (unrounded)
= 3 (rounded)
Hope this helps!
C pretty sure if not sorry
Answer:
87.54 g of H₂O₂
Explanation:
From the question given above, the following data were obtained:
Number of molecules = 1.55×10²⁴ molecules
Mass of H₂O₂ =.?
From Avogadro's hypothesis,
6.02×10²³ molecules = 1 mole of H₂O₂
Next, we shall determine the mass of 1 mole of H₂O₂. This can be obtained as follow:
1 mole of H₂O₂ = (2×1) + (2×16)
= 2 + 32
= 34 g
Thus,
6.02×10²³ molecules = 34 g of H₂O₂
Finally, we shall determine mass of H₂O₂ that contains 1.55×10²⁴ molecules. This can be obtained as follow:
6.02×10²³ molecules = 34 g of H₂O₂
Therefore,
1.55×10²⁴ molecules
= (1.55×10²⁴ × 34)/6.02×10²³
1.55×10²⁴ molecules = 87.54 g of H₂O₂
Thus, 87.54 g of H₂O₂ contains 1.55×10²⁴ molecules.
Answer:
45 °C.
Explanation:
From the question given above, the following data were obtained:
Heat (Q) = 1125 J
Mass (M) = 250 g
Final temperature (T₂) = 55 °C
Specific heat capacity (C) = 0.45 J/gºC
Initial temperature (T₁) =?
The initial temperature of the iron can be obtained as illustrated below:
Q = MC(T₂ – T₁)
1125 = 250 × 0.45 (55 – T₁)
1125 = 112.5 (55 – T₁)
Divide both side by 112.5
1125/112.5 = 55 – T₁
10 = 55 – T₁
Collect like terms
10 – 55 = –T₁
–45 = –T₁
Multiply through by –1
45 = T₁
T₁ = 45 °C
Therefore, the initial temperature of the iron is 45 °C
