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3 years ago

Calcium has an atomic number of 20. How many electrons of a calcium atom are involved in chemical bonding?

Chemistry

1 answer:

NARA [144]3 years ago

3 0

The answer is 2 electrons.

The electron configuration of calcium is 2:8:8:2

Calcium has two electrons in its outermost shell. These are its valence electrons and are the ones used in bonding with other elements. Valence electrons of an atom are those electrons that are in its outer energy shell or that are available for bonding.

Calcium is a metal. When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms forming ions. The resulting compound is known as an ionic compound.

For example, when calcium metal reacts with chlorine gas, calcium gives up its two valence electrons and Chlorine accepts them resulting in a new substance called calcium chloride in which the two elements have ended up forming ionic bonds.

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The p-value of a statistical test depends on all of the following, except:

vaieri [72.5K]

Answer:

The correct option is e.

Explanation:

p-value is the probability value for a given statistical model, the probability that, when the null hypothesis is true.

For two two samples the formula of test statistics is

$t=\frac{(\overline{x}_1-\overline{x}_2)-(\mu_1-\mu_2)}{\sqrt{\frac{s_1^2}{n_1}+\frac{s_2^2}{n_2}}}$

where,

$\overline{x}$ is sample mean

$\mu$ is population mean.

$s$ is standard deviation.

n is sample size.

Variance is the square of standard deviation.

It means variance, mean, numbers of samples is used in calculation of p-value.

Degree of freedom define the shape of the t-distribution that your t-test uses to calculate the p-value.

$d.f.=n_1+n_2-2$

p-value of a statistical test depends on all of the following, except median.

Therefore the correct option is e.

4 0

3 years ago

(2-2) Looking at the chemical formula CaF2 (calcium fluoride), what do you think this substance is made of? (Choose ALL that app

mixer [17]

Answer:

Metal

Non-metal

Explanation:

CaF2 is an ionic compound. Ionic compounds are mostly composed of a metal and a non metal. Metals donate electrons to non-metals to form ionic compounds.

Calcium is a divalent ion of group two in the periodic table while F is a univalent nonmetal of group 17 in the periodic table. Hence the compound CaF2 is composed of a metal and a nonmetal.

7 0

3 years ago

According to the law of conservation of mass, what should the product side of this single replacement reaction look like? A. H2

Katyanochek1 [597]

Answer: The product side must be $ZnCl_2+H_2$

Explanation:

Single displacement reaction is defined as the reaction in which more reactive metal displaces a less reactive metal from its chemical reaction.

$AB+C\rightarrow CB+A$

Metal C is more reactive than metal A.

The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.

Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form. This also means that total number of individual atoms on reactant side must be equal to the total number of individual atoms on the product side.

When zinc metal reacts with hydrochloric acid, it leads to the production of zinc chloride and hydrogen gas. The chemical reaction follows:

$Zn+2HCl\rightarrow ZnCl_2+H_2$

On reactant side:

Number of zinc atoms = 1

Number of hydrogen atoms = 2

Number of chlorine atoms = 2

On product side:

Number of zinc atoms = 1

Number of hydrogen atoms = 2

Number of chlorine atoms = 2

Hence, the product side must be $ZnCl_2+H_2$

8 0

3 years ago

What is the temperature of CO2 gas if the average speed (actually the root-mean-square speed) of the molecules is 750 m/s?

erastova [34]

Answer:

992.302 K

Explanation:

V(rms) = 750 m/s

V(rms) = √(3RT / M)

V = velocity of the gas

R = ideal gas constant = 8.314 J/mol.K

T = temperature of the gas

M = molar mass of the gas

Molar mass of CO₂ = [12 + (16*2)] = 12+32 = 44g/mol

Molar mass = 0.044kg/mol

From

½ M*V² = 3 / 2 RT

MV² = 3RT

K = constant

V² = 3RT / M

V = √(3RT / M)

So, from V = √(3RT / M)

V² = 3RT / M

V² * M = 3RT

T = (V² * M) / 3R

T = (750² * 0.044) / 3 * 8.314

T = 24750000 / 24.942

T = 992.302K

The temperature of the gas is 992.302K

Note : molar mass of the gas was converted from g/mol to kg/mol so the value can change depending on whichever one you use.

3 0

2 years ago

List the following molecules in order of increasing boiling point: Br2, Cl2, F2, I2.

Andrej [43]

Answer:

1. None of these have hydrogen bonding.

2. None of these have dipoles.

3. Bigger molecules will have stronger London dispersion forces. So I2 has the strongest forces,

and F2 will have the weakest. Correspondingly, I2 will have the highest boiling point and F2 will have the lowest boiling point.

Answer: F2, Cl2, Br2, I2

Explanation:

7 0

3 years ago

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