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fomenos
2 years ago
8

An object in space is made of gas and gives off light and heat energy. We can only see it at night. Which object is it? (2 point

s)
Earth
moon
star
sun
Chemistry
1 answer:
strojnjashka [21]2 years ago
7 0

Answer:

stars

earth isn't made of gas. (and you can always see it)

moon us not gas, or give off heat

sun is only visible during the day

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What is the daughter nuclide when 0-15 experiences positron emission?
Helen [10]

The daughter isotope (a decay product)of O-15 = N-15(Nitrogen 15)

<h3>Further explanation </h3>

Radioactivity is the process of unstable isotopes to stable isotopes by decay, by emitting certain particles,  

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  • beta β ₋₁e⁰ particles
  • gamma particles γ
  • positron particles ₁e⁰

O-15 emits positron particles ₁e⁰, so the atomic number decreases by 1, the mass number is the same

Reaction

 \tt _8^{15}O\Rightarrow _7^{15}N+_1^0e

The mass number of the daughter isotope = 15, atomic number = 7

If we look at the periodic system, the element with atomic number 7 is Nitrogen (N)

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2 years ago
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dolphi86 [110]

g - Measurement of Mass

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5 0
3 years ago
A volume of 25.36 ± 0.05 mL 25.36±0.05 mL of HNO 3 HNO3 solution was required for complete reaction with 0.8311 ± 0.0007 g 0.831
Sholpan [36]

Answer:

MOLARITY= 0.3092mol/l

ABSOLUTE UNCERTAINTY= 0.000873

Explanation:

The equation of reaction is

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Molarity= gram mole of solute ÷ liters of solution

Where;

Mole of solute= mass ÷ molar mass

Therefore;

Mole of solute= 0.8311g ÷ 105.988g/mol= 0.0078515mol

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This is the Molarity of the solution

QUESTION2: CALCULATION FOR ABSOLUTE UNCERTAINTY;

Uncertainty (u) =√([0.05 ÷ 25.36]^2 + [0.001 ÷ 105.988]^2 + [0.0007 ÷ 0.8311]^2) × Molarity

Solving brackets gives

(0.00197161+0.00000943503+0.00084226) ×Molarity

Adding up gives

0.002823×Molarity

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3 years ago
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Answer:

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4 0
3 years ago
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Hello!

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Have a nice day!
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