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3 years ago

Which element has four energy levels? Na,K,Cs,Rb

Chemistry

2 answers:

Ann [662]3 years ago

7 0

Potassium K

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Alik [6]3 years ago

6 0

Answer:

The correct option is: Potassium

Explanation:

Sodium, Potassium, Rubidium and Caesium are referred to as the alkali metals that belong to the group 1 of the periodic table, thus having one valence electron in their outer or valence shell.

Sodium, atomic number 11, belongs to the period 3 of the periodic table. It has three shells and the number of electrons per shell is 2, 8, 1.

Potassium, atomic number 19, belongs to the period 4 of the periodic table. It has four shells and the number of electrons per shell is 2, 8, 8, 1.

Rubidium, atomic number 37, belongs to the period 5 of the periodic table. It has five shells and the number of electrons per shell is 2, 8, 18, 8, 1.

Caesium, atomic number 37, belongs to the period 6 of the periodic table. It has six shells and the number of electrons per shell is 2, 8, 18, 18, 8, 1.

Therefore, Potassium, atomic number 19, has four shells or energy levels.

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A sound wave has a wavelength of 0.7 miles and a frequency of 500 Hertz what is the speed

yaroslaw [1]

speed equals wavelength times frequency so

.7 x 500 = 350

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3 years ago

What is the concentration of a solution?

Nimfa-mama [501]

The concentration of a substance is the quantity of solute present in a given quantity of solution.

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3 years ago

How many moles of gas are in a 1.0 liter canister if the temperature of the canister is 100 K and the pressure is 100 atmosphere

ladessa [460]

Answer:

n = 12.18 moles

Explanation:

Given that,

The volume of a canister, V = 1 L

The temperature of the canister, T = 100 K

Pressure, P = 100 atm

We need to find the number of moles of gas. Let there are n number of moles. We know that,

PV = nRT

Where

R is gas constant, R = 0.0821 L*atm/mol*K

$n=\dfrac{PV}{RT}\\\\n=\dfrac{100\times 1}{0.0821 \times 100}\\\\n=12.18\ moles$

Hence, there are 12.18 moles of gas.

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3 years ago

Which statements are correct about silicon?

ki77a [65]

Answer:

A. Metalloid

E. Has similar properties as Ge

F. Belongs to Period 3

Explanation:

Silicon is the 14th element on the periodic table. Its unit is SI. Its properties straddles between those of metals and non-metals and it is described as a non-metal.

It's atomic weight or mass number is 28u. It has an atomic number of 14 i.e in its neutral state, the number of protons and electrons are equal to 14.

Silicon belongs to the 4th group and the 3rd period on the periodic table. Elements in the same group share similar chemical properties. The elements in Si group are: C, Ge, Sn and Pb. The properties of Si is similar to these elements because they all have a valency of 4. Across the period, the properties varies this is why Si would have a very different property from Al and P.

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3 years ago

Which two characteristics describe all animals

Maru [420]

All animals can be dangerous and they would fight for their family. (This might be wrong)

5 0

3 years ago