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4 years ago

What is the answer please and why is this answer

Chemistry

1 answer:

natulia [17]4 years ago

3 0

Answer:

2 & 4

Explanation:

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Adding what two values gives the mass of an atom?

Eduardwww [97]

The protons and neutrons

8 0

3 years ago

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7.49 x 105 mm 34500 inches 0.45 miles 885 yards smallest to largest lengths

emmasim [6.3K]

30.962
34500
28512
31860

answer:

7.49 x 105 mm
0.45 miles
885 yards
34500 inches

reason:

I converted all the measurements to inches.
First, I multiplied 7.49x105 to get 786.45mm
Then, I divided it by 25.4 to get about 30.92 inches

Next, I converted 0.45 miles to inches by multiplying it by 63,360 to get 28,512 inches

For the yards, I took 885 and multiplied it by 36 to get 31,860 inches

Since the last one was already in inches, all I needed to do was put them in order from least to greatest

6 0

3 years ago

What mass of silver chloride (m = 143.4) will dissolve in 1.00 l of water? the ksp of agcl is 1.8 × 10–10 ?

trapecia [35]

Given that solubility product of AgCl = 1.8 X 10^-10

Dissociation of AgCl can be represented as follows,

AgCl(s) ↔ Ag+(ag) + Cl-(aq)

Let, [Ag+] = [Cl-] = S

∴Ksp = [Ag+][Cl-] = S^2

∴ S = √Ksp = √(1.8 X 10^-10) = 1.34 x 10^-5 mol/dm3

Now, Molarity of solution = $\frac{\text{weight of solute}}{\text{Molecular weight X volume of solution (l)}}$
∴ 1.34 x 10^-5 = $\frac{\text{weight of AgCl}}{143.4 X 1}$
∴ Weight of AgCl present in solution = 1.92 X 10^-3 g

Thus, mass of AgCl that will dissolve in 1l water = 1.92 x 10^-3 g

7 0

3 years ago

An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about 4.4x 10 m/s Calculate the

otez555 [7]

The question is incomplete, here is the complete question:

An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about $4.4\times 10^6m/s$ . Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of helium. Write your answer as a percentage of the average speed, and round it to 2 significant digits

Answer: The percentage of average speed is 41 %

Explanation:

We are given:

Radius of helium atom = 31 pm = $31\times 10^{-12}m$ (Conversion factor: $1m=10^{12}pm$ )

So, diameter of helium atom = $(2\times r)=(2\times 31\times 10^{-12})=64\times 10^{-12}m$

The diameter of the atom will be equal to the uncertainty in position.

The equation representing Heisenberg's uncertainty principle follows:

$\Delta x.\Delta p=\frac{h}{2\pi}$

where,

$\Delta x$ = uncertainty in position = d = $64\times 10^{-12}m$

$\Delta p$ = uncertainty in momentum = $m\Delta v$

m = mass of electron = $9.1095\times 10^{-31}kg$

h = Planck's constant = $6.627\times 10^{-34}kgm^2/s^2$

Putting values in above equation, we get:

$64\times 10^{-12}m\times 9.1095\times 10^{-31}kg\times \Delta v=\frac{6.627\times 10^{-34}kgm^2/s}{2\times 3.14}\\\\\Delta v=\frac{6.627\times 10^{-34}kgm^2/s^2}{2\times 3.14\times 64\times 10^{-12}m\times 9.1095\times 10^{-31}kg}=1.81\times 10^6m/s$

To calculate the percentage of average speed, we use the equation:

$\text{Percentage of the average speed}=\frac{\text{Uncertainty in velocity}}{\text{Average orbital speed}}\times 100$

We are given:

Average orbital speed = $4.4\times 10^6m/s$

Putting values in above equation, we get:

$\text{Percentage of the average speed}=\frac{1.81\times 10^6m/s}{4.4\times 10^6m/s}\times 100\\\\\text{Percentage of the average speed}=41.\%$

Hence, the percentage of average speed is 41 %

3 0

4 years ago

Considering that the mantle is 44.8% oxygen and 21.5% silicon by mass, calculate the mole ratio of oxygen atoms to silicon atoms

horrorfan [7]

The mantle has a mass of around $4.278 X 10 ^2^4 kg$ that is around 68.4% of earth's mass.

So to calculate moles we need to first find out the mass of oxygen and silicon present in mantle. It is given that oxygen is 44.8% by mass in mantle and 21.5% by mass in mantle, therefore to calculate its mass, we need to use $\text{mass percentage }=\frac{\text{mole of solute}}{\text{mass of solution}}\times100$

Now, to calculate mass percentage of oxygen

$44.8 =\frac{x}{4.278X10^2^4kg}\times100$

$x= 191.65\times10^2^2kg$

Similarly the mass of silicon can be calculated

$21.5 =\frac{x}{4.278X10^2^4kg}\times100$

$x=91.977\times10^2^2kg$

Now, the moles of any substance is calculated by

$\text{moles}= \frac{\text{given mass}}{\text{molar mass}}$

$\text{moles of oxygen}= \frac{191.65\times10^2^2kg}{2.6566962\times10^-^2^6kg}$

where, mass of oxygen in kilograms is $2.6566962\times10^-^2^6kg$

So, $\text{moles of oxygen}=72.1384\times10^4^8\text{moles of O}$

Similarly $\text{moles of silicon}= \frac{91.977\times10^2^2kg}{4.663\times10^-^2^6kg}$

$\text{moles of silicon}=19.724\times10^4^8\text{moles of Si}$

Now, to calculate mole ratio we need to divide every moles to the lowest calculated mole that is the moles of Si and round it off to the nearest whole number.

$\text{mole ratio of oxygen}= \frac{72.138\times10^4^8kg}{19.724\times10^4^8kg}$

$=3.65\approx 4$

$\text{mole ratio of Silicon}=\frac{19.724\times10^4^8}{19.724\times10^4^8}$

$=1$

$\text{Mole ratio of Oxygen : Mole ratio of Silicon} = 4:1$

6 0

4 years ago

Read 2 more answers