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DedPeter [7]
3 years ago
14

Which of these elements is a metal? Hafnium Radon Silicon Sulfur Selenium

Chemistry
2 answers:
Gre4nikov [31]3 years ago
6 0
Selenium is a non metal, radon is a noble gas, silicon is a metalloid, and sulphur is a non metal. Hafnium is a transition metal.
natali 33 [55]3 years ago
6 0

Answer:

Hafnium

Explanation:

Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals

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KNO3(s) --> K+(aq) + NO3-(aq)
ella [17]

Answer:

KNO₃(s) + 35,1 kJ → K⁺(aq) + NO₃⁻(aq)

Explanation:

In the reaction:

KNO₃(s) → K⁺(aq) + NO₃⁻(aq)

The <em><u>heat absorbed</u></em> for the reaction (Because the temperature decreases) is:

Q = C×m×ΔT

Where C is specific heat (4,18J/g°C); m is mass (100g); ΔT is (30,0°C-21,6°C = 8,4°C)

Replacing:

Q = 4,18J/g°C×100g×8,4°C

<em><u>Q = 3511 J</u></em>

Now, moles of KNO₃ are:

10,1g×(1mol / 101g) = <em><u>0,1 moles.</u></em>

Heat of solution in kJ/mol is:

3,511 J / 0,1 mol = <em><u>35,1 kJ</u></em>

As the heat was absorbed for the reaction, right answer is:

<em>KNO₃(s) + 35,1 kJ → K⁺(aq) + NO₃⁻(aq)</em>

That means the reaction needs the heat to occurs.

I hope it helps!

6 0
3 years ago
What is the density of a 19.3-gram object that displaces 12 cubed centimeters of water
KIM [24]

Answer:

1.608 g/cm3

Explanation:

Formula:

D=m/v

d= density

m= mass

v= volume

Given data:

Mass= 19.3 g

Volume= 12 cm3

The volume of water displaces by object is 12 cm³ which means that object hold the volume of 12 cm³

Now we will put the values in formula:

D=19.3 g/ 12 cm3= 1.608 g/cm3

so the density of object is 1.608 g/cm3

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What is the name of the compound CO?\
xxTIMURxx [149]
Carbon Monoxide is the correct answer
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Asparagine is a polar amino acid shown here at ph 7 what is the maximum
KonstantinChe [14]
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3 0
3 years ago
Which evidence is an indication that a chemical reaction has occurred?
Luden [163]

Answer:

  • Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.

8 0
2 years ago
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