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3 years ago

How does the ionosphere affect radio frequencies?

1 answer:

6 0

Due to the ability of ionized atmospheric gases to refract high frequency (HF, or shortwave) radio waves, the ionosphere can reflect radio waves directed into the sky back toward the Earth. Radio waves directed at an angle into the sky can return to Earth beyond the horizon.

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You have 100 mL of a 12M solution of HCl, and you need to dilute it to 1.5M for an experiment. How many liters will your new sol

sashaice [31]

Answer:

800.0 mL.

Explanation:

To solve this problem; we must mention the rule states the no. of millimoles of a substance before and after dilution is the same.

(MV)before dilution of HCl = (MV)after dilution of HCl

M before dilution = 12.0 M, V before dilution = 100.0 mL.

M after dilution = 1.5 M, V after dilution = ??? mL.

∵ (MV)before dilution of HCl = (MV)after dilution of HCl

∴ (12.0 M)(100.0 mL) = (1.5 M)(V after dilution of HCl)

∴ V after dilution of HCl = (12.0 M)(100.0 mL)/(1`.5 M) = 800.0 mL.

8 0

3 years ago

Determine the enthalpy change when 23.5 g of carbon is reacted with oxygen according to the reaction C(s) + O2(g) CO2(g) delta H

xeze [42]

We are provided with the amount of energy released when one mole of carbon reacts. We mus first convert the given mass of carbon to moles and then compute the energy released for the given amount.

Moles = mass / atomic mass
Moles = 23.5 / 12
Moles = 1.96 moles

One mole releases 394 kJ/mol
1.96 moles will release:
394*1.96
= 772.24

The enthalpy change of the reaction will be -772.24 kJ

8 0

3 years ago

Which statement correctly describes metallic bonds?

lions [1.4K]

Answer: D

Explanation:

the atom of the metal loses one electron which becomes delocalised and is attragted by the positive nucleus leading to formation of metallic bond.

5 0

3 years ago

A reaction progress curve has three peaks and two valleys between the peaks. This curve describes a reaction mechanism that invo

katrin [286]

Answer:
A reaction progress curve has three peaks and two valleys between the peaks. This curve describes a reaction mechanism that involves three elementary reactions.

Explanation:
I have drawn the progress curve with three peaks and two valleys. In fact the peaks shows higher energy and valleys show lower energies. So, Let suppose we react A and B. This reaction between A and B results in the formation of C. In this reaction the energies of A and B are less, and during the progress of reaction they cross a transition state of higher energy and forms product C with lower energy which is present at lower valley. This was first reaction. Other two reactions will be followed by conversion of C to D and conversion of D into E.

3 0

3 years ago

Read 2 more answers

Which elemental clues contain sufficient info to place the element using no other info

zaharov [31]

Atomic number

Explanation:

The atomic number is enough clue that can be used to proper place elements without any other information. The atomic number is the number of protons in an atom. Protons are positively charged particles in the nucleus of an atom.

To place elements on the periodic table, the periodic law which states that "properties of elements are a periodic function of their atomic number" must be obeyed.
Using the atomic number, one can determine the number of electrons in a neutral atom, the charges on an ion e.t.c.
Atomic number can also be used to write the electronic configuration of an atom be it the shell notation, sublevel notation and the lewis dot structure.

Learn more:

Atomic numbers brainly.com/question/5425825

About atomic numbers brainly.com/question/1379579

Electronic configuration brainly.com/question/549647

#learnwithBrainly

8 0

3 years ago