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3 years ago

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

Chemistry

2 answers:

Marat540 [252]3 years ago

7 0

It has 2 valence electrons

THANK ME

Shkiper50 [21]3 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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Which best describes a reaction in a state of equilibrium?

tamaranim1 [39]

The best statement which describes a reaction in a state of equilibrium is letter D. The rate of the forward reaction equals the rate of the reverse reaction and the concentrations of products and reactants are constant.

>Chemical equilibrium is defined as the state in which both reactants and products are present in concentrations which have no further tendency to change with time. This state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but equal. Thus, there are no net changes in the concentrations of the reactant(s) and product(s).

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2 years ago

Match the word to the part of the wave. (Lesson 4.02)

Alenkinab [10]

Answer:

1 A. Wavelength 2. B. Crest 3. C. Amplitude 4. D. Trough

Explanation:

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2 years ago

A student obtains the following data: Mass of empty, dry graduated cylinder: 21.577 g Volume added of NaCl solution: 4.602 mL Ma

klasskru [66]

Answer: The density of NaCl solution is 3.930 g/mL

Explanation:

We are given:

Mass of cylinder, $m_1$ = 21.577 g

Mass of NaCl and cylinder combined, M = 39.664 g

Mass of NaCl, $m_2$ = $(M-m_1)=(39.664-21.577)g=18.087g$

To calculate density of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

We are given:

Mass of NaCl = 18.087 g

Volume of NaCl solution = 4.602 mL

Putting values in above equation, we get:

$\text{Density of NaCl}=\frac{18.087g}{4.602mL}\\\\\text{Density of NaCl}=3.930g/mL$

Hence, the density of NaCl solution is 3.930 g/mL

7 0

2 years ago

What is the daughter nucleus (nuclide) produced when 64 Cu Cu64 undergoes beta decay by emitting an electron? Replace each quest

kenny6666 [7]

Answer: The daughter nuclide formed by the beta decay of given isotope is $_{30}^{64}\textrm{Zn}$

Explanation:

Beta decay is defined as the process in which beta particle is emitted. In this process, a neutron gets converted to a proton and an electron.

The released beta particle is also known as electron.

$_Z^A\textrm{X}\rightarrow _{Z+1}^A\textrm{Y}+_{-1}^0\beta$

We are given:

Parent isotope = $_{29}^{64}\textrm{Cu}$

The chemical equation for the beta decay process of $_{29}^{64}\textrm{Cu}$ follows:

$_{29}^{64}\textrm{Cu}\rightarrow _{30}^{64}\textrm{Zn}+_{-1}^0\beta$

Hence, the daughter nuclide formed by the beta decay of given isotope is $_{30}^{64}\textrm{Zn}$

4 0

3 years ago

Helium has a density of 1.79 x 10-4 g/mL at standard temperature and pressure. A balloon has a volume of 6.3 liters. Calculate t

LenaWriter [7]

The density of He is 1.79 x 10⁻⁴ g/mL
In other words in 1 mL there's 1.79 x 10⁻⁴ g of He.
To fill a volume of 6.3 L the mass of He required
= 1.79 x 10⁻⁴ g/mL * 6300 mL
= 11 277 * 10⁻⁴ g
Therefore mass of He required = 1.1277 g of He

8 0

3 years ago

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