I need help in chemistry!!!!!!!!!!!

Answer:

A

Explanation:

A mixture is formed when two or more substances are physically mixed together. A compound is formed when two or more substances are chemically combined through a chemical reaction.

Answer:

11

Explanation:

Explanation:

The lack of a control group

Answer:

The tilt of the Earth's axis also defines the length of daylight.Daylight hours are shortest in each hemisphere winter. Between summer and winter

solistice the number of daylight hours decreases and the rate of decrease is larger the higher the latitude.The fewer sunlight hours the colder nights.

Answer:

20

Explanation:

Answer: 3:2

Explanation: (10.14÷3.38)÷(8.42÷4.21)=1.5=3/2

Answer:

B: The colors of light emitted from heated atoms had very specific energies.

Explanation:

dont know if its the same question i had on edg but i think its B. Sorry if i didnt understand the question :)

Answer:

b

Explanation:

Answer:

21

Explanation:9+10

NO can't  be used to fill a balloon

Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters/mol.

Answer options that need to be added :

a. Ne

b. NO

c. NH₃

d. CH₄

e. HF

will float in air ⇒ element or compound to fill the balloon, its density must be less than < 1.285 g/L

We can use the ideal gas formula ta find density :

[tex]\tt \rho=\dfrac{P.MW}{RT}[/tex]

Because at STP, then the constant value is

[tex]\tt \rho=\dfrac{1~atm\times MW}{0.08205\times 273.15~K}\\\\\rho=0.0446\times MW[/tex]

So that the density is determined from the MW(molecular weight) of each element or compound

Ar = 20.1797 g/mol

[tex]\tt \rho=0.0446\times 20.1797=0.9~g/L[/tex]

MW=30.006 g/mol

[tex]\tt \rho=0.0446\times 30.006=\boxed{\bold{1.338~g/L}}[/tex]

MW=17.0306 g/mol

[tex]\tt \rho=0.0446\times 17.0306=0.760~g/L[/tex]

MW=16.04 g/mol

[tex]\tt \rho=0.0446\times 16.04=0.715~g/L[/tex]

MW=20.01 g/mol

[tex]\tt \rho=0.0446\times 20.01=0.892~g/L[/tex]

Answer:

Phosphorus trioxide

Explanation:

Answer:

Tetraphosphorus hexoxide

Explanation:

Give brainliest please

Answer:

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

From the question

density = 2 g/ml

volume = final volume of water - initial volume of water

volume = 508 - 500 = 8 mL

We have

mass = 2 × 8

We have the final answer as

Hope this helps you

Answer:

3.05x10²³ (3 sig. fig.)

Explanation:

Propane (C₃H₈) is a colorless alkane gas with three carbons and eight hydrogen atoms. In 2.23 grams of propane, there are 3.05 x 10²³ carbon atoms present.

The number of atoms or the particles being the smallest units is estimated by the product of the number of moles and Avogadro's number.

The Avogadro's number (Na) is used to determine the number of particles that have been present in a mole of a substance. A mole of a substance is said to have 6.022 × 10²³ ions, atoms, electrons, molecules, etc.

Moles of propane are calculated as,

Moles = mass ÷ molar mass

= 2.23 ÷ 440.094

= 0.05057

Now, the number of particles is calculated as,

Number = moles × Avogadro's number

= 0.05057 × 6.022 × 10²³

= 3.05 x 10²³

Therefore, 3.05 x 10²³ carbon atoms are present in 2.23 grams of propane.

Learn more about the number of particles/atoms here:

https://brainly.com/question/11884840

#SPJ2

Explanation:

Potassium is a chemical element with the symbol K and atomic number 19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure

Answer:

Explanation:

Answer:

Mass = 0.000176 gram

Steps:

m =  V × ρ

=  20 milliliter × 8.8 gram/cubic meter

=  2.0E-5 cubic meter × 8.8 gram/cubic meter

=  0.000176 gram

Explanation:

Answer:

B

Explanation:

Mass number  = number of neutrons + number of protons

Atomic number is the number of protons in the nucleus.  

58Ni   : 58 is the number of neutrons + number of protons

atomic number of Ni is 28.  Thus,  58 -28 = 30 neutrons

57Co ;  57 is the number of neutrons + number of protons

number of Co is 27. Thus, 57 – 27  = 30 neutrons

Answer:

Explanation:

Noble gases are the least reactive of all known elements. That's because with eight valence electrons, their outer energy levels are full. The only exception is helium, which has just two electrons.

What is the DNA strand? You have not named it.

Answer:

=0.00123

Explanation:

Look at the attachments below

Hope this helps (:

Answer:

0.00123

Explanation:

Standard notation is the normal way of writing numbers. Examples include 1, 2, and 10. The number 1.23 x 10^-3 is written in scientific notation. The decimal goes after the first nonzero integer and it is multiplied by a power of 10. The power or exponent attached to the 10 tells you how many places over you need to move the decimal to get back into scientific notation. Examples include 1.00 x 10^2 (representing 100 in standard form because you would move the decimal two places to the right.), 2.0 x 10^1 (representing 20 in standard form because you would move the decimal one place to the right), and 3.0 x 10^-4 (representing 0.0003 in standard form because you would move the decimal four places to the left since it is a negative exponent).

The negative (-3) exponent in 1.23 x 10^-3 indicated to move the decimal three places to the left. If it was positive, you would move it three places to the right.

In 1.23 x 10^-3 move the decimal to the left 1 place to get:

0.123

two places to get:

0.0123

and a third place to get:

0.00123

The final answer is 0.00123

iondine

Explanation:

bromine has 185pm, astatine haa 200, iondine has 140 and lastly fluorine has 147. so iondine has the smallest atomic radius

Answer:

A wave is phenomenon that transfers energy from one point to another through a disturbance without affecting the matter.

Explanation:

A wave is phenomenon that transfers energy from one point to another through a disturbance without affecting the matter.

Answer:

explanations below

Explanation:

The alkaline earth metals are the 6 chemical elements that can be found in group two of the periodic table. These elements have a lot of properties in common, in the sense that they are generally shiny, reactive at standard temperature and pressure and they are also silvery-white. The elements are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra)

These metals have two electrons at their orbits, which can be easily lost to form cations (with charge +2, and an oxidation state of +2)  

Below are some of their details

Name: Beryllium  

Number of Protons/Electrons: 4  

Number of Neutrons: 5  

Name: Magnesium  

Number of Protons/Electrons: 12  

Number of Neutrons: 12  

Name: Calcium  

Number of Protons/Electrons: 20  

Number of Neutrons: 20  

Name: Strontium  

Number of Protons/Electrons: 38  

Number of Neutrons: 50  

Name: Barium  

Number of Protons/Electrons: 56  

Number of Neutrons: 81  

Name: Radium  

Number of Protons/Electrons: 88  

Number of Neutrons: 138  

Ah yes.

The atomic radius is basically the distance between the nucleus of the atom and the outermost electron in the farthest orbital of the atom. The more bigger the atomic radius , the less powerful is the force that holds together the nucleus and its electrons.

Answer:

Mg is more reactive than Cu

Explanation:

In the reaction between Mg and CuO to form MgO, MgO will form because Mg is more reactive than Cu.

This kind of reaction is called a single replacement or single displacement reaction.

Answer:

Inner space

Explanation:

I hope this helps

Answer:

Explanation:

option A is correct