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3 years ago

What rules should you follow when adding and subtracting ?

2 answers:

5 0

Adding and subtracting with scientific notation may require more care, because the rule for adding and subtracting exponential expressions is that the expressions must havelike terms<span>. Remember that to be </span>like terms<span>, two expressions must have exactly the same base numbers to exactly the same powers. Thinking about decimal arithmetic, the requirement that we have the same powers makes sense, because that guarantees that all of the place values are lined up properly.</span>

german3 years ago

4 0

Negative - Negative = Negative.
Positive - Negative = Positive
Negative - Positive = Negative
Negative + Negative = Negative
Positive + Positive = Positive

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How many hydrogen atoms are in 105 g of water?

mel-nik [20]

Moles of water atoms = mass/molecular weight = 105/18 = 5.83 mol. Number of moles of hydrogen in water = 2 x moles of water = 11.66. Number of H atoms in water = moles of hydrogen x 6.02 x 10^23 = 7.019 x 10^24 ~ 7.02 x 10^24 atoms. Hope this helps.

3 0

3 years ago

2 Ag20 →4 Ag + O2 what reaction is this

Schach [20]

Answer:

Decomposition

Explanation:

hope it helps you

6 0

3 years ago

Astroturf is a durable artificial surface used to cover athletic fields. A soccer field 0.06214- mile-long by 253 ft wide is cov

love history [14]

Answer:

The weight of the Astroturf is 179,684.31 Newtons.

Explanation:

Length of a soccer field = 0.06214 mile = 328.0992 feet

(1 mile = 5280 feet)

Breadth of a soccer field = 253 feet

Length of a Astroturf which soccer field is to be covered, l = 328.0992 feet

Breadth of a Astroturf which soccer field is to be covered ,b = 253 feet

Thickness of a Astroturf with which soccer field is to be covered = h

h = ½ inch = 0.5 inch = 0.041665 feet

(1 inches = 0.08333 feet)

Volume of the Astroturf ,V= l × b × h

$V=328.0992 ft\times 253 ft\times 0.041665 ft=3,458.574 ft^3$

Mass of the Astroturf = m

Density of the Astroturf = d = 187 $oz/ft^3$

$d=\frac{m}{V}$

$m=d\times V= 187 oz/ft^3\times 3,458.574 ft^3=646,753.35 oz$

1 oz = 0.0283495 kg

$m=646,743.35 oz=646,743.35\times 0.0283495 kg=18,335.13 kg$

Weight of the Astroturf = W

W = mg

$=W=18,335.13 kg\times 9.8 m/s^2=179,684.31 N$

The weight of the Astroturf is 179,684.31 Newtons.

8 0

3 years ago

An atom is neutral. Its nucleus contains two protons and two neutrons. How

garri49 [273]

Answer:

we need to know which atom you're talking about and then you need to say what the mass number is then we can tell how many electrons there are.

(I think)

3 0

2 years ago

Read 2 more answers

If 24.6 grams of lithium react with excess water, how many liters of hydrogen gas can be produced at 301 Kelvin and 1.01 atmosph

andreev551 [17]

Answer: 43.3 l

Explanation:

1) Chemical equation:
2 Li(s) + 2 H₂O (l) → 2LiOH(aq) + H₂ (g)

2) Mole ratios:

2 mol Li : 2 mol H₂O : 2 mol LiOH : 1 mol H₂

3) Number of moles of Li that react

n = mass in grams / atomic mass = 24.6g / 6.941 g/mol = 3.54 moles

4) Yield

Proportion:

2 mol Li / 1 mol H₂ = 3.54 mol Li/ x

⇒ x = 3.54 mol Li × 1 mol H / 2 mol Li = 1.77 mol H₂

4) Ideal gas equation

PV = nRT ⇒ V = nRT / P

V = 1.77 mol × 0.0821 [atm×l / (mol×K)] × 301 K / 1.01 atm = 43.3 l

V = 43.3 l ← answer

7 0

3 years ago