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Nesterboy [21]
4 years ago
13

What is true about the element calcium(Ca, atomic number 20)? Choose all that apply.

Chemistry
2 answers:
Marat540 [252]4 years ago
7 0
It has 2 valence electrons

THANK ME
Shkiper50 [21]4 years ago
5 0

Answer:

It has 2 valence electrons

It is a metal.

Explanation:

Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal.

In chemistry, a metal is an element that readily forms positive ions (cations) by losing electrons.

Calcium belongs to group 2 and would give up it's two valence electrons in reactions.

The electronic configuration is given as;

Ca : 1s2 2s2 2p6 3s2 3p6 4s2 or [Ar] 4s²

Valence electron represents the outermost electrons.

The correct options are;

It has 2 valence electrons

It is a metal.

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A balloon containing helium gas expands from 230
andre [41]

Answer:

1.0 *10^(-4) mol

Explanation:

For gases:

n1/n2 = V1/V2

n1/3.8*10^(-4) mol = 230 mL/ 860 mL

n1 = 3.8*10^(-4)*230/860 = 1.0 *10^(-4) mol

5 0
3 years ago
How much CaCO3 would have to be decomposed to produce 247 g of CaO
vovangra [49]

441 g CaCO₃ would have to be decomposed to produce 247 g of CaO

<h3>Further explanation</h3>

Reaction

Decomposition of CaCO₃

CaCO₃ ⇒ CaO + CO₂

mass CaO = 247 g

mol of CaO(MW=56 g/mol) :

\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{247}{56}\\\\mol=4.41

From equation, mol ratio CaCO₃ : CaO = 1 : 1, so mol CaO :

\tt \dfrac{1}{1}\times 4.41=4.41

mass CaCO₃(MW=100 g/mol) :

\tt mass=mol\times MW\\\\mass=4.41\times 100\\\\mass=441~g

6 0
3 years ago
When H2(g) reacts with Cl2(g) to form HCl(g) , 185 kJ of energy are evolved for each mole of H2(g) that reacts. Write a balanced
Katyanochek1 [597]

Answer:

H₂(g) + Cl₂(g) → 2HCl(g) + 185kJ

Explanation:

In a chemical reaction, enthalpy of reaction ΔH is a thermodynamic constant that gives information if the reaction is exothermic (Produce heat if reacts) or endothermic (Consume heat if reacts).

In the reaction:

H₂(g) + Cl₂(g) → 2HCl(g) ΔH = -185kJ

As ΔH <0, the reaction is exothermic, that means, <em>produce heat</em>, writing a balanced thermochemical equation:

<em>H₂(g) + Cl₂(g) → 2HCl(g) + 185kJ</em>

<em></em>

The enthalpy is as a product beacause an exothermic reaction produces heat.

I hope it helps!

<em></em>

7 0
4 years ago
Why did mendeleev leave blank spaces in his version of the periodic table?.
Leviafan [203]
<h2>Answer: He left blank spaces for <em>undiscovered</em> elements to be added to the table.</h2>

Explanation:

3 0
2 years ago
Read 2 more answers
Which element is presented in all organic compounds
DerKrebs [107]
Carbon and hydrogen
3 0
4 years ago
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