How many electrons are in Br-? A) 4 B) 7 C) 34 D) 36 E) none of the above

Answers

Answer 1

Answer: The number of electrons in Br- (bromide ion) is option B) 7.

Bromine (Br) has an atomic number of 35, which means it normally has 35 electrons. However, since the bromide ion (Br-) has a negative charge, it has gained one extra electron, bringing the total number of electrons to 35 + 1 = 36.

So, the correct answer is not listed among the options given

c

Explanation:

Which element has the greatest density at STP?(1) scandium (3) silicon
(2) selenium (4) sodium

Answers

Answer:

Selenium has the greatest density at STP.

Explanation:

According to Ideal gas equation,

P V = n R T

where;

n = m/M

Therefore,

P V = m R T / M

Rearranging,

P M = (m/V) R T

Also,

m/V = density = d

So,

P M = d R T

Solving for density,

d = P M / R T

According to this equation density is directly proportional to Molar mass of a substance. Hence, the Atomic masses of given compounds are listed below,

Scandium = 44.96 g.mol⁻¹

Selenium = 78.97 g.mol⁻¹

Silicon = 28.09 g.mol⁻¹

Sodium = 22.99 g.mol⁻¹

Therefore, selenium having the greatest Atomic Mass will have the greatest density. The densities of given elements are as follow;

Scandium = 2.98 g.cm⁻³

Selenium = 4.81 g.cm⁻³

Silicon = 2.33 g.cm⁻³

Sodium = 0.96 g.cm⁻³

$\boxed{\left( 2 \right){\text{ Selenium}}}$ has the greatest density at STP.

Further Explanation:

Ideal gas law is the equation of state for any hypothetical gas. The expression for the ideal gas equation is as follows:

${\text{PV}} = {\text{nRT}}$ …… (1)

Here,

P is the pressure.

V is the volume.

T is the absolute temperature.

n is the number of moles.

R is the universal gas constant.

The formula to calculate the number of moles is as follows:

${\text{n}}=\frac{{\text{m}}}{{\text{M}}}$ ...... (2)

Here,

n is the number of moles.

m is the mass.

M is the molar mass.

Substitute the value of n from equation (2) in equation (1).

${\text{PV}} = \frac{{{\text{mRT}}}}{{\text{M}}}$ …… (3)

Rearrange equation (3) as follows:

${\text{PM}} = \frac{{{\text{mRT}}}}{{\text{V}}}$ …… (4)

The formula to calculate density is as follows:

${\rho }} = \frac{{\text{m}}}{{\text{V}}}$ ...... (5)

Here,

${\rho }}$ is the density.

m is the mass.

V is the volume.

Substitute equation (5) in equation (4).

${\text{PM}} = \rho{\text{RT}}$ …… (6)

Rearrange equation (6) to calculate the density.

${\rho }} = \frac{{{\text{PM}}}}{{{\text{RT}}}}$ ...... (7)

At STP, T and P remain constant, R is already a constant. So according to equation (7), density of substance is directly proportional to the molar mass of the substance.

The molar mass of scandium is 44.96 g/mol.

The molar mass of selenium is 78.97 g/mol.

The molar mass of silicon is 28.09 g/mol.

The molar mass of sodium is 22.99 g/mol.

The molar mass of selenium is the highest among the given elements so its density will be the greatest.

Learn more:

1. Which statement is true for Boyle’s law: brainly.com/question/1158880

2. Calculation of volume of gas: brainly.com/question/3636135

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Ideal gas equation

Keywords: P, V, n, R, T, ideal gas, pressure, volume, selenium, sodium, scandium, silicon, 22.99 g/mol, 78.97 g/mol, 28.09 g/mol, 44.96 g/mol, density, molar mass.

Heelp plsWhich element has the lowest electronegativity?
nitrogen (N)
lithium (Li)
bromine (Br)
potassium (K)

Answers

Answer: Potassium (K) has the lowest electronegativity among the given elements.

Explanation:

Electronegativity is a measure of an element's ability to attract electrons towards itself when it is involved in a chemical bond with another element. Potassium has the lowest electronegativity because it has only one valence electron that is located far from the nucleus, making it easier to lose that electron and become a positively charged ion. In contrast, nitrogen, lithium, and bromine have higher electronegativities because they have more valence electrons or the valence electrons are closer to the nucleus, making it more difficult to remove or share electrons.

The element with the lowest electronegativity among the given options is potassium (K). Potassium has an electronegativity value of approximately 0.82 on the Pauling scale, which is the lowest value among the four elements listed. In contrast, nitrogen (N) has an electronegativity of approximately 3.04, bromine (Br) has an electronegativity of approximately 2.96, and lithium (Li) has an electronegativity of approximately 0.98. Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. The lower the electronegativity value, the less the atom attracts electrons towards itself.

Brainliest?

In which block of the periodic table is chromium (Cr) found?

Answers

The correct answer for above statement:

chromium is in group 6 d-block

Explanation:

The d-block elements are designated transition metals and have valence electrons in d orbital's. The f-block elements, observed in the two rows at the ground of the periodic table, are called inner transition metals and have valence electrons in the f-orbital's.

Chromium is a synthetic element with symbol Cr and atomic number 24. It is the first component in group 6. It is a steely-gray, glistening, dense and brittle metal which takes a high polish, resists smudging, and has a great melting point.

chromium is in group 6 d-block

According to the law of conservation of energy, the energy released by the system must be transferred to and absorbed by the surroundings

Answers

True!
Energy released by system is absorbed by surroundings.

Is the following chemical equation balanced?

2Na + 2H2O 2NaOH + H2

Answers

Answer: YES

Explanation: The given chemical equation can be balanced by balancing the stiochiometric number of each and every element.

This rule is in accordance with the Law of Conservation of Masses which states that the masses of the elements in any chemical equation are constant at any instant of time.

Thus the given equation can be written as

$2Na + 2H2O \rightleftharpoons 2NaOH + H2$