A runner completes a 400m race in 43.9s. What is his average speed?

Answer:

In chemistry, the letter "H" represents the enthalpy of a system

Explanation:

Answer:

p = 43, n = 57, e = 40

Explanation:

Z is the number of protons. The number of neutrons, subtract Z from the isotope number (100). To begin with, protons and electrons are equal in an atom, but this atom lost three, so subtract 3 from Z.

Z= # of protons = 43

100 - 43 = 57 neutrons

43 - 3 = 40 electrons.

Answer:

Trough is the lower bound of wave, while the crest is the upper bound of a wave.

Explanation:

see picture attatched

Answer:

chemical equation balance.

Explanation:

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Answer:

Ag-107 has an abundance of 51.82% and mass of 106.9 amu

Explanation:

Answer:

Naturally occurring silver ( 47Ag ) is composed of the two stable isotopes 107Ag and 109Ag in almost equal proportions , with 107Ag being slightly more abundant ( 51.839 % natural abundance ) .

Hope this helps

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question

mass = 324 g

volume = 40.8 cm³

We have

[tex]density = \frac{324}{40.8} \\ = 7.941176...[/tex]

We have the final answer as

Hope this helps you

Answer:

3 g/mL

Explanation:

Density is mass divided by volume (g/mL).

Mass of rock = 12.5

Volume of rock = 24-20 = 4mL

Density of rock = 12.5g/ 4mL = 3.125 g/mL

Round to the lowest number of significant figures which is 1 to get 3 g/mL

Answer:

KF

Explanation:

Potassium = K

Fluoride = F

[tex]K^{+1}F^{-1}K_{1} F_{1}=KF[/tex]

Answer:

KF is your answer. Can I get Brainliest

Answer:

I think it's 1, but if that's wrong I'm really sorry

Answer:

A variable in an experiment which is held constant in order to assess the relationship between multiple variables, is a control variable.

Explanation:

Answer:

After the reaction, the total mass of the products must be D. Less than 10.0 grams

Answer: +3

Explanation: Gallium liquefies just above room temperature. Gallium is a soft solid, however it quickly becomes liquid when heated.

Answer:

WHY DO YOU NEED HELP HUH

DON'T CHEAT READ AND STUDY

Explanation:

Answer:

It's C

Explanation:

Answer:

0.5×10² pm

Explanation:

Given data:

Frequency of x-ray = 6×10¹⁸ Hz

Wavelength of x-ray = ?

Solution:

Wavelength is designated as "λ" and it is the measured in meter. It is the distance between the two crust of two trough.

Formula:

speed of wave = wavelength × frequency

speed = 3×10⁸ m/s

now we will put the values in formula.

3×10⁸ m/s = λ  × 6×10¹⁸ Hz

Hz = s⁻¹

λ  = 3×10⁸ m/s / 6×10¹⁸ s⁻¹

λ  = 0.5×10⁻¹⁰ m

m to pm

0.5×10⁻¹⁰ m × 10¹² pm/1m

0.5×10² pm

Answer:

Explanation:

In order to find the new volume we use the formula for Boyle's law which is

[tex]P_1V_1 = P_2V_2[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

Since we are finding the new volume

[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]

We have

[tex]V_2 = \frac{10 \times 2}{4} = \frac{20}{4} \\ [/tex]

We have the final answer as

Hope this helps you

First balance the equation:

4NH3 + 3O2 ↔ 2N2 + 6H2O

Check that the equation is balanced properly by checking the numbers of each element are equal:

LS

N - 1x4 = 4

H - 3x4 = 12

O - 2x3 = 6

RS

N - 2x2 = 4

H - 2x6 = 12

O - 1x6 = 6

Given the equation is balanced properly, we can find the sum of the coefficents by adding.

4 + 3 + 2 + 6 = 15

Therefore, the sum of the coeffiecents is 15.

Answer:

55

Explanation:

According to the law of conservation properties of Matter in a closed system the mass of reactants is equal to the mass of products. Because there is no lose of matter or energy in closed system

Answer:

The boiling point increases with increased pressure up to the critical point, where the gas and liquid properties become identical.

Answer:

...

Explanation:

Answer:

It is 'A' i.e., Sodium magnesium, aluminium

Elements tend to lose and gain electrons to achieve electronic stability. Lithium, sodium, and potassium are the elements that form +1 ions. Thus, option C is correct.

Cations are said to be the ions formed by donating their outermost valence electron that in return results in a positive charge on the element. Cations are said to be formed when the electron is more in number in the valence shell.

The electronic configuration is given as:

Here, there is one electron extra in the outer shell of the atom that can be donated to other atoms that are called anions (electron acceptors). Li, Na, and K can donate one electron each and hence will acquire a +1 charge.

Therefore, option C. lithium, sodium, and potassium form a +1 charge.

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The volume of cylinder = 7.948 cm³

Further explanation

Volume is a derivative quantity derived from the length of the principal

The unit of volume can be expressed in liters or milliliters or cubic meters

The volume of the aquarium is almost the same as the beam namely:

V = length x width x height

The volume of a cylinder can be formulated :

[tex]\tt V=\pi.r^2.h[/tex]

r = radius

h = height

Diameter of cylinder = 1.25 cm

radius=r :

[tex]\tt \dfrac{1.25}{2}=0.625~cm[/tex]

[tex]\tt V=\pi\times 0.625^2\times 6.48\\\\V=\boxed{\bold{7.948~cm^3}}[/tex]

Answer:

The answer is C, Glucose is a compound, because it is made of more than one element.

Explanation:

Complete Question is ;

The chemical formula for glucose, a type of sugar, is C₆H₁₂0₆. Which statement is true about glucose?

1) Glucose is a compound because it's made from more than 1 element

2) Glucose is an element because it's made up from more than one kind of atom.

3) Glucose is an element because it can be separated.

4) glucose is a compound because is made of protons, neutrons and electrons

Solution ;

The statement which is true about glucose is (1) Glucose is a compound because it's made from more than 1 element. Hence the correct option is (1)

Aan element made entirely of one species of atoms, or an atom which has a specific number of protons in its nucleus.

Chemical elements, in contrast to chemical compounds, cannot be reduced by any chemical process into simpler molecules.

Three substances make up glucose: carbon, hydrogen, and oxygen. They are set at a fixed ratio of 1:2:1.

Covalent bonds, in which two atoms share bonding valence electrons in one or more bonds, are used to bind these atoms together.

Therefore, The statement which is true about glucose is (1) Glucose is a compound because it's made from more than 1 element. Hence the correct option is (1)

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Answer:

all

of them

Explanation:

Answer:

Part A:

A physical change is a change of a substance from one form to another without changing its composition.

Part B:

A physical change is a change of a substance from one form to another without changing its composition. Example: A balloon deflating into its original form.

A chemical change occurs, one substance combines with another substance to make something completely new. Example: Making and baking a cake.

Answer:

2.48626 x 10^24

Explanation:

We multiple 4.13 by avogadro's number to get that.

Alkanes are saturated hydrocarbons that have single bonds in chains

General formula for alkanes :

[tex]\tt \large{\bold{C_nH_{2n+2}}[/tex]

Hydrocarbon combustion reactions (specifically alkanes)

[tex]\large {\box {\bold{C_nH _ (_2_n _ + _ 2_) + \dfrac {3n + 1} {2} O_2 \Rightarrow nCO_2 + (n + 1) H_2O}}}[/tex]

So that the burning of ethane with air (oxygen):

[tex]\tt C_2H_6+\dfrac{7}{2}O_2\rightarrow 2CO_2+3H_2O[/tex]

2C₂H₆ (g) + 7O₂ (g) ⟶ 4CO₂ (g) + 6H₂O (ℓ)

or we can use mathematical equations to solve equilibrium chemical equations by giving the coefficients for each compound involved in the reaction

C₂H₆ (g) + aO₂ (g) ⟶ bCO₂ (g) + cH₂O (ℓ)

C : left 2, right b ⇒ b=2

H: left 6, right 2c⇒ 2c=6⇒ c= 3

O : left 2a, right 2b+c⇒ 2a=2b+c⇒2a=2.2+3⇒2a=7⇒a=7/2

Answer:

Differences in temperature cause differences in air density. Warmer air is less dense than cold, which is why warm air tends to rise and cold air sinks.

temparature affects particles. warm particles are more spread out.

Explanation:

. Being acted on by gravity, colder, denser air weighs more and exerts greater pressure per unit area.

Answer:

O microwaves, radio waves, infrared light

Explanation:

Answer: C.  microwaves, radio waves, infrared light

Explanation: C. Microwaves, Radio Waves, Infrared light