Answer:
C₅H₁₀O₅
Explanation:
1. Calculate the mass of each element in 2.78 mg of X.
(a) Mass of C

(b) Mass of H

(c) Mass of O
Mass of O = 3.5 - 1.400 - 0.2349 = 1.87 g
2. Calculate the moles of each element

3. Calculate the molar ratios
Divide all moles by the smallest number of moles.

4. Round the ratios to the nearest integer
C:H:O = 1:2:1
5. Write the empirical formula
The empirical formula is CH₂O.
6. Calculate the molecular formula.
EF Mass = (12.01 + 2.016 + 16.00) u = 30.03 u
The molecular formula is an integral multiple of the empirical formula.
MF = (EF)ₙ

MF = (CH₂O)₅ = C₅H₁₀O₅
The molecular formula of X is C₅H₁₀O₅.
Reaction: 2K₍s₎ + 2H₂O₍l₎ → 2KOH₍aq₎ + H₂₍g₎.
K - potassium.
H₂O - water.
KOH - potassium-hydroxide.
H₂ - hydrogen.
s - solid phase.
l - liquid.
aq - disolves in water.
g - gas.
Reaction is exothermal (release of energy) and potassium burns a purple flame. H<span>ydrogen released during the reaction reacts with </span>oxygen<span> and ignites.</span><span>
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It’s the first 1 M yea it’s the first one
Answer: The coefficient is 3.645
The exponent is 1
There are 4 significant digits
The rightmost significant figure is 5
Explanation:
Scientific notation is defined as the representation of expressing the numbers that are too big or too small and are represented in the decimal form with one digit before the decimal point times 10 raise to the power.
For example : 5000 is written as 
According to avogadro's law, 1 mole of every gas contains avogadro's number
of particles, occupy 22.4 L at STP and weighs equal to its molecular mass.
131.29 g of Xe occupy = 22.4 L at STP.
Thus 213.62 g of
occupy =
at STP.
Scientific notation = 
The coefficient is 3.645
The exponent is 1
There are 4 significant digits
The rightmost significant figure is 5
Picoliter is a unit of measurement for liquids.
One picoliter = 1×10⁻⁹ mililiters
So:
19 mL ---- x pL
1×10⁻⁹ mL ---- 1 pL
1×10⁻⁹x = 19
x = 1,9 × 10¹⁰ pL
or 19,000,000,000 pL
Answer: 1.9 × 10¹⁰ pL