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3 years ago

Balance the following chemical equation _Na + _Br2 —> _ NaBr

Chemistry

1 answer:

ehidna [41]3 years ago

3 0

Answer:

2, 1, 2

Explanation:

Na + Br2 —> NaBr

To balance the equation, we do the following:

There are 2 atoms of Br on the right side and 1atom on the left side. It can be balance by putting 2 in front of NaBr as shown below:

Na + Br2 —> 2NaBr

Now, we have 2 atoms of Na on the right side and 1atom on the left. Thus, it can be balance by putting 2 in front of Na as shown below:

2Na + Br2 —> 2NaBr

Now, the equation is balanced.

The coefficients are 2, 1, 2

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The average score for games played in the NFL is 21.1 and the standard deviation is 8.9 points. 46 games are randomly selected.

kaheart [24]

Answer:

A) P(21.4317 < ¯x < 22.7561) = 0.2975

B) Q1 for the ¯x distribution = 21.9844

Explanation:

The Central Limit theorem allows us to say that

Sample mean = Population mean = 21.1 points

Mean of sampling distribution = σₓ = (σ/√n)

σ = population standard deviation = 8.9 points

n = sample size = 46

σₓ = (8.9/√46) = 1.3122334098 = 1.3122

A) P(21.4317 < ¯x < 22.7561) =

This is a normal distribution problem

To find this probability, we will use the normal probability tables

We first normalize/standardize 21.4317 and 22.7561.

The standardized score of any value is that value minus the mean divided by the standard deviation.

For 21.4317

z = (x - μ)/σ = (21.4317 - 21.1)/1.3122 = 0.25

For 22.7561

z = (x - μ)/σ = (22.7561 - 21.1)/1.3122 = 1.26

The required probability

P(21.4317 < ¯x < 22.7561) = P(0.25 < z < 1.26)

Checking the tables

P(21.4317 < ¯x < 22.7561) = P(0.25 < z < 1.26)

= P(z < 1.26) - P(z < 0.25)

= 0.89617 - 0.59871

= 0.29746 = 0.2975 to 4 d.p.

B) Q1 for the distribution is the first quartile. The first quartile is greater than 25% of the distribution.

P(x > Q1) = 0.25

Let the z-score that corresponds to Q1 be z'

P(x > Q1) = P(z > z') = 0.25

But P(z > z') = 1 - P(z ≤ z') = 0.25

P(z ≤ z') = 1 - 0.25 = 0.75

From the normal distribution tables,

z' = 0.674

z' = (Q1 - μ)/σ

0.674 = (Q1 - 21.1)/1.3122

Q1 = 0.674×1.3122 + 21.1 = 21.9844228 = 21.9844 to 4 d.p.

Hope this Helps!!!

7 0

3 years ago

Write the dissociation equation for NH4OH.

iVinArrow [24]

Explanation:

NH4OH(aq) ---> NH4+(aq) + OH-(aq)

7 0

3 years ago

Calculate the number of atoms in 2.5 moles of Si.

Ede4ka [16]

Answer:

$\boxed {\boxed {\sf About \ 1.5 * 10^{24} \ atoms \ Si}}$

Explanation:

When converting from moles to atoms, we must use Avogadro's number. This number tells us there are 6.022 * 10²³ atoms in 1 mole. We can multiply this number by the number of moles.

First, we must set up Avogadro's number as a ratio.

$\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}$

Next, multiply the number of moles by the ratio.

$2.5 \ mol \ Si *\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}$

When we multiply, the moles of silicon will cancel.

$2.5 * \frac {6.022 \ * 10^{23} \ atoms \ Si }{1}}$

Since the denominator of the fraction is 1, we can cancel it out too.

$2.5 * {6.022 \ * 10^{23} \ atoms \ Si }$

$1.5055 * 10^{24} \ atoms \ Si$

The original measurement (2.5 moles) has 2 significant figures (2 and 5). Therefore we must round to 2 sig figs. For this question, 2 sig figs is the tenth place.

The 0 in the hundredth place tells us to leave the 5 in the tenth place.

$1.5 * 10^{24} \ atoms \ Si$

There are about <u>1.5 * 10²⁴ atoms of silicon.</u>

7 0

3 years ago

The power source for all electrical objects must be a what

mariarad [96]

A circuit is a closed loop that electrons can travel in. A source of electricity, such as a battery, provides electrical energy in the circuit. ... The appliance may, for example, provide light or heat or mechanical energy.

6 0

3 years ago

How do you convert 16.7 inches to feet?

beks73 [17]

There are 12 inches in a foot.

16.7 in ÷ 12 in = 1.39 ft

Or if you prefer to the nearest tenth:

1.4 ft.

Good luck! :)

6 0

3 years ago

Read 2 more answers