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3 years ago

Which of the following elements would make a 2- ion? A. N B. O C. Si D. Mg

Chemistry

1 answer:

nataly862011 [7]3 years ago

3 0

Answer:

oxygen

Explanation:

because the 2nd shell is not complete which is suppose to be 8 and since oxygen is 8 it first shell is 2 which is complete and the second shell which is 6 is not complete because we all know that 2+6=8 but the standard shell is

K-2

L-8

M-8

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Which actions represent endothermic reactions? Check all that apply.

marishachu [46]

Answer:

Well, one is if heat is absorbed by the system from the surroundings, the system gains heat from the surroundings and so the temperature of the surroundings decreases.

Explanation:

8 0

3 years ago

Read 2 more answers

I NEED HELP PLEASE, THANKS! :)

krok68 [10]

Answer:

$\large \boxed{\text{2.20 g Pb}}$

Explanation:

They gave us the masses of two reactants and asked us to determine the mass of the product.

This looks like a limiting reactant problem.

1. Assemble the information

We will need a chemical equation with masses and molar masses, so, let's gather all the information in one place.

Mᵣ: 239.27 32.00 207.2

2PbS + 3O₂ ⟶ 2Pb + 2SO₃

m/g: 2.54 1.88

2. Calculate the moles of each reactant

$\text{Moles of PbS} = \text{2.54 g PbS } \times \dfrac{\text{1 mol PbS}}{\text{239.27 g PbS}} = \text{0.010 62 mol PbS}\\\\\text{Moles of O}_{2} = \text{1.88 g O}_{2} \times \dfrac{\text{1 mol O}_{2}}{\text{32.00 g O}_{2}} = \text{0.058 75 mol O}_{2}$

3. Calculate the moles of Pb from each reactant

$\textbf{From PbS:}\\\text{Moles of Pb} = \text{0.010 62 mol PbS} \times \dfrac{\text{2 mol Pb}}{\text{2 mol PbS}} = \text{0.010 62 mol Pb}\\\\\textbf{From O}_{2}:\\\text{Moles of Pb} =\text{0.058 75 mol O}_{2} \times \dfrac{\text{2 mol Pb}}{\text{3 mol O}_{2}}= \text{0.039 17 mol Pb}\\\\\text{PbS is the $\textbf{limiting reactant}$ because it gives fewer moles of Pb}$

4. Calculate the mass of Pb

$\text{ Mass of Pb} = \text{0.010 62 mol Pb} \times \dfrac{\text{207.2 g Pb}}{\text{1 mol Pb}} = \textbf{2.20 g Pb}\\\\\text{The reaction produces $\large \boxed{\textbf{2.20 g Pb}}$}$

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2 years ago

Electronegativity values increase from left to right across a period in the periodic table because there is an increase in the c

Mademuasel [1]

First, let us define Electronegativity. Electronegativity is "the ability of an atom to attract electrons." In addition, electronegativity increases in elements from left to right, while on the other hand, electronegativity decreases from top to bottom in an element group. It decreases because the atomic radius increases as we go downward an element in the group.

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3 years ago

The average adult heart pumps about 84. mL/s of blood at 72 beats per minute. Suppose you need to calculate how long it would ta

dalvyx [7]

Explanation:

Rate = 84mL/s

A minute has 60 seconds;

Rate = 84mL/s * 60s = 5040 mL/minute

Volume of blood in a minute = Rate * Number of beeats per minute

Volume = 5040 * 72 = 362880 mL

How long to circulate 3500ml?

1 minute = 362880mL

x = 3500 mL

x = 3500mL min / 362880mL

Math Expression:

Time to circulate 3500ml of blood (min) = 3500ml * 1 minute / Volume of blood at a rate of 84ml/s and 72 beats per minute (ml)

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3 years ago

Which of these elements has an electron configuration of [Kr]5s2?

beks73 [17]

Strontium has an electron configuration of [Kr]5s²

<h3>Further explanation </h3>

In an atom there are levels of energy in the shell and sub shell

This energy level is expressed in the form of electron configurations.

Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d and f. The maximum number of electrons for each sub shell is

s: 2 electrons

p: 6 electrons

d: 10 electrons and

f: 14 electrons

From an electron configuration of [Kr]5s² can be concluded :

element is in period 5 (5 = shell)
element is group 2(valence electron =2 and block s)
has atomic number 38 (Kr = 36 + 2(valence elektron from 5s²)

If we look at the periodic system, the elements that meet the requirements in question are Strontium (Sr)

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3 years ago