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emmasim [6.3K]
3 years ago
5

What number should be substituted for the question mark to balance the equation and why is that the correct number?

Physics
2 answers:
grigory [225]3 years ago
6 0
The combustion of ethane results in the balanced equation 2C2H6 + 7O2 -> 4CO2 + H2O + energy because we see that after the combustion, the reactants have 8 + 6 = 14 Oxygen atoms in total (8 from 4CO2, 6 from 6H2O). Therefore, since there are 2 atoms of Oxygen in oxygen gas, we have 7O2 molecules in the beginning to hold the ratio true.
sergeinik [125]3 years ago
6 0
To balance an equation, we need to make sure the amount of atoms on the reactants and the products. 

How much oxygen's are on the reactants side? 

Lets count, 4*2 = 8  and 6, so 8+6 = 14

Now, start to predict the number. 

14/2 = 7

Answer: 7 is the correct answer
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Elza [17]

1) push down on the end of the lever, and 2) 3/4 of the way from the fulcrum

7 0
3 years ago
What is the least force you could exert on the refrigerator to move it?
Ulleksa [173]
 <span>If the refrigerator weights 1365 and you are not exerting any vertical force on it, then the normal force is also 1365N. so Fn=1365 

Fsf = Static frictional force = (coefficient of static friction) * (Normal force) 

So the least for you could exert to move it is equal to the Fsf. 
Fsf = (0.49)(1365N)</span><span>
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8 0
3 years ago
A wire of length 5mm and Diameter 2m extends by 0.25 when a force of 50N was use. calculate the
bazaltina [42]

Answer and Explanation:

Data provided in the question

Force = 50N

Length = 5mm

diameter = 2.0m = 2\times 10^{-3}

Extended by = 0.25mm = 0.25\times 10^{-3}

Based on the above information, the calculation is as follows

a. The Stress of the wire is

= \frac{force\ applied}{area\ of \ circle}

here area of circle = perpendicular to the are i.e cross-sectional  i.e

= \frac{\pi d^{2}}{4}

= \frac{\pi(2\times 10^{-3})^2}{4}

Now place these above values to the above formula

= \frac{4\times 50}{\pi\times 4 \times 10^{-6}} \\\\ = \frac{50}{\pi}

= 15.92 MPa

As 1Pa = 1 by N m^2

So,

MPa = 10^6 N m^2

b. Now the strain of the wire is

= \frac{Change\ in\ length}{initial\ length} \\\\ = \frac{0.25\times 10^{-3}}{5}

= 5 \times 10^{-5}

3 0
3 years ago
What happens to the density of ocean water when salinity increases? A. It increases. B. It decreases. C. It becomes variable. D.
omeli [17]
A. It increases... but slightly. Good luck!
3 0
3 years ago
When objects exchange charge, why do we say it's the negative charge that moves and not the positive?
Novay_Z [31]

Answer:

It is said that the negative charge moves because the electrons in the atoms of any object are taken or given to the atoms of another object.

Explanation:

The atom is made up of protons, electrons and neutrons. The number of protons is exactly the same to the number of electrons for a certain element. For example, hydrogen: it has a proton, and therefore, an electron.

The electron has a negative charge. The proton has a positive charge. And the neutron has no charge, so it is neutral. While the atom has the same number of protons and electrons, it will not be electrically charged.

An example of how a charge exchange occurs between two objects is through the case of rubbing. This makes the atoms of the two objects close enough that there is an electron transfer, causing any of the objects to gain or lose electrons as a consequence of each other interaction. In the case of transferring electrons, the atom will have a greater number of protons, so it will be positively charged. When the atom receive electrons, it will have a greater number of electrons, so it will be negatively charged.

Therefore, since it is the electrons that move from one atom to another, then it is the negative charge that moves (<em>characterized by the electrons</em>) and not the positive charge (<em>characterized by the protons</em>).

6 0
3 years ago
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