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WITCHER [35]
2 years ago
8

In 1803, the British chemist John Dalton proposed several atomic theories. Which one of his theories was later shown to be incor

rect?
I. Atoms are indivisible and indestructible particles.

II. All atoms of the same element are exactly alike.

III. Atoms of different elements are different.

IV. Atoms combine in specific numerical ratios to form compounds.

A. II only
B. II & III only
C. I & II only
Chemistry
1 answer:
Serggg [28]2 years ago
6 0
Option C: I and II only.

The atoms have subparticles and the isotops are atoms of the same element that differ in the number of neutrons.
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Analyze the example of this door knob wheel and axle.
bulgar [2K]

Answer:

28

Explanation:

Velocity ratio= Radius of wheel/radius of axle

Radius of wheel= 4.125 inches

Radius of axle= 0.125 inches

Velocity ratio = 4.125/0.125 = 33

Then;

Efficiency = mechanical advantage/velocity ratio × 100

Since the efficiency of the system = 85%

85 = mechanical advantage/33 × 100

Mechanical advantage = 85 × 33/100 = 28

4 0
2 years ago
The combustion of propane occurs when propane interacts with oxygen gas to produce water and carbon dioxide in the following rea
gtnhenbr [62]

Answer:

  • 20 atm

Explanation:

<u>1) Data:</u>

a) n = 2 moles

b) T = 373 K

c) V = 2.5 liter

d) P = ?

<u>2) Chemical principles and formula</u>

You need to calculate the pressure of the propane gas in the mixture before reacting. So, you can apply the partial pressure principle which states that each gas exerts a pressure as if it occupies the entire volume.

Thus, you just have to use the ideal gas equation: PV = nRT

<u>3) Solution:</u>

  • PV = nRT ⇒ P = nRT / V

P = 2 mol × 0.08206 atm-liter /K-mol × 373K / 2.5 liter = 24.5 atm

Since the number of moles are reported with one significant figure, you must round your answer to one significant figure, and that is 20 atm (20 is closer to 24.5 than to 30).

5 0
2 years ago
The concentration of ozone in a sample of air that has a partial pressure of O3 of 0.33 torr and a total pressure of air of 695
Goryan [66]

Answer:

0.047 %

Explanation:

Step 1: Given data

  • Partial pressure of ozone (pO₃): 0.33 torr
  • Total pressure of air (P): 695 torr

Step 2: Calculate the %v/v of ozone in the air

Air is a mixture of gases. We can find the %v/v of ozone (a component) in the air (mixture) using the following expression.

<em>%v/v = pO₃/P × 100%</em>

%v/v = 0.33 torr/695 torr × 100%

%v/v = 0.047 %

8 0
2 years ago
Given the following balanced reaction of hydrochloric acid and oxygen gas forming chlorine gas and water, how many grams of hydr
nadya68 [22]
The ratio of moles of reactants to moles of products can be seen from the coefficients in a balanced equation. In our case  4 moles of hydrochloric acid reacts with one mole of oxygen to produce two moles of chlorine and water.  So, <span> the ratio of moles of hydrochloric acid to moles of chlorine is 2:1. To determine the number moles, divide the mass by the mass of one mole. </span>
<span>Cl2 = 2 * 35.45 = 70.9 grams </span>
<span>Number of moles = 335 ÷ 70.9 </span>
<span>This is approximately 4.72 moles. The number of moles of hydrochloric acid is twice this number. </span>

<span>Mass of one mole = 1 + 35.46 = 36.45 grams </span>
<span>Total mass = 2 * (335 ÷ 70.9) * 36.45 </span>
<span>This is approximately 344.45 grams. 
Correct answer A.</span>
6 0
2 years ago
Read 2 more answers
A sample of TNT, C7H5N3O6 , has 8.94 × 1021 nitrogen atoms. How many hydrogen atoms are there in this sample of TNT?
Bess [88]

Answer:

1.49×10²² atoms of H are contained in the sample

Explanation:

TNT → C₇H₅N₃O₆

1 mol of this has 7 moles of C, 5 moles of H, 3 moles of N and 6 moles of O

Let's determine the mass of TNT.

Molar mass is = 227 g/mol

As 1 mol has (6.02×10²³) NA atoms, how many moles are 8.94×10²¹ atoms.

8.94×10²¹ atoms / NA = 0.0148 moles

So this would be the rule of three to determine the mass of TNT

3 moles of N are in 227 g of compound

0.0148 moles of N are contained in (0.0148 .227) / 3 = 1.12 g

Now we can work with the hydrogen.

227 grams of TNT contain 5 moles of H

1.12 grams of TNT would contain (1.12 .5) / 227 = 0.0247 moles

Finally let's convert this moles to atoms:

0.0247 mol . 6.02×10²³ atoms / 1 mol = 1.49×10²² atoms

8 0
2 years ago
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