Answer:
the newspaper one is a chemical change because the chemicals in the paper have reacted with something and turned a different color. the wax one is a physical change because it is a change in the phase of matter, which is always a physical change (still the same substance chemically)
Answer:
The mass of coke needed to react completely with 1.0 ton of copper(II) oxide is 0.794 Ton.
Explanation:

1 Ton = 907185 grams
Mass of copper oxide = 1.0 Ton = 907185 grams
Moles of copper oxide =
According to reaction, 2 moles of copper oxide reacts with 1 mole of carbon.
Then 11403.95 moles of copper oxide will react with:
of carbon
Mass of 5,701.98 moles of carbon:

Mass of coke = x
Mass of carbon = 68,423.75 g
Percentage of carbon in coke = 95%


The mass of coke needed to react completely with 1.0 ton of copper(II) oxide is 0.794 Ton.
Answer:
250000 μL
Explanation:
If 1 L = 1000 mL
Then X L = 250 mL
X = (1 × 250) / 1000 = 0.25 L
Now we can calculate the number of microliters (μL) in 0.25 L:
if 1 μL = 10⁻⁶ L
then X μL = 0.25 L
X = (1 × 0.25) / 10⁻⁶ =250000 μL
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