please help!! my grades dying
15 points

Answer:

I think it is Lithium...

Explanation:

Answer:

Sabihin mo

Explanation:

salamat shoppe

Answer:

Plumbing System

Explanation:

Answer:

C plumbing system

Explanation:

Infrastructure is the basic structures needed for the operation of society

Answer:

separate soluble solids from liquid

Explanation:

A in Chemistry

Crystallization is a separation technique used to separate solute solids from a liquid solvent.

Crystallization is the process of disuniting or separating two substances or molecules that are mixed, and are of different forms of matter. Such as solid and liquid. The process separates mixtures by three processes. These processes are freezing, precipitation, and deposition.

It is the main process of separating solid from liquid. In this process, the solute came above the liquid in crystal form and this is called precipitation.  

Freezing separates the substance that has a different freezing point.  By deposition, the substance that is solid and called solute is deposited below the liquid in the container.    

Thus, crystallization separates the solute solids from a liquid solvent.

To learn more about Crystallization, refer to the link:

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Answer:

t

Explanation:

because for atoms to change they have to have some kind of chemical action to get new life

Answer:

No, this is invalid. The term mono in front of monoatomic simply refers to the number of atoms that are present in a compound or simply by itself it has no relationship with respect to the overall charge of the compound.

Explanation:

For instance Ca is considered as a monoatomic ion but it has a charge of +2.

Answer:

Nutrients advance through the alimentary canal to the stomach and small intestine, and waste materials continue from the small intestine to the colon (large intestine) and anus.

Explanation:

Answer:

cation

Explanation:

a cation is an ion with a postitive charge. This (cat)ion (+) = cats are good , anion (onion) are not good (-)

Answer:

c. no reaction happens

Explanation:

Let me take your mind back to the idea of electrode potentials of metals. Remember that the more negative the electrode potential of a metal, the more reducing the metal is. Metals with more negative electrode potentials displace metals with less negative electrode potentials from their aqueous solutions.

The electrode potential of nickel is -0.25 V while that of copper is +0.34 V. Hence, copper is lower than nickel in the activity series and can not displace it from aqueous solution.

This implies that, if a piece of copper metal is placed in a solution that contains nickel(II) ions, no reaction happens .

Answer:

balance for the 1st and mass for the 2nd

Answer:

Its D :)

Or not i haven't done this in a while-

Answer:

The chemical formula for water is H2O which means that every molecule of water has 2 atoms of hydrogen (H) and one atom of oxygen (O). Here comes the key part. From the Periodic Table of Elements, one sees that one mole of hydrogen atoms weighs 1 gram while one mole of oxygen atoms weighs 16 grams.

Explanation:

:)

The number of atoms present in two water molecules is 6 atoms. 4 hydrogen atoms and 2 oxygen atoms.

Atoms are the basic unit of a substance. An atom is made of a nucleus, protons, neutrons and electrons. Different atoms combines to form a molecule and molecules combines to form compounds.

Water has the formulas H₂O, thus one molecule of water contains 2 hydrogen and one oxygen. Therefore, two molecules of water that is (H₂O)₂ have 4 hydrogen and 2 oxygens thus, a total of 6 atoms.

Hence, the number of atoms present in two molecules of water is 6.

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Answer: The footprints were made [tex]2.99\times 10^6years[/tex] years long ago.

Explanation:

Radioactive decay follows first order kinetics.

Half-life of isotope X= 500,000 years

[tex]\lambda =\frac{0.693}{t_{\frac{1}{2}}}=\frac{0.693}{500000}=0.00000139year^{-1}[/tex]

The equation for first order kinetics is :

[tex]N=N_o\times e^{-\lambda t}[/tex]

N = amount left after time t  = 0.125 mg

[tex]N_0[/tex] = initial amount  = 8.00 mg

[tex]\lambda[/tex] = rate constant

t= time  

Putting the values we get:

[tex]0.125=8.00\times e^{- 0.00000139years^{-1}\times t}[/tex]

[tex]0.0156=e^{- 0.00000139years^{-1}\times t}[/tex]

[tex]t=2.99\times 10^6years[/tex]

The footprints were made [tex]2.99\times 10^6years[/tex] years long ago.

Answer:

hkile uo gihme rapre

Explanation:

The indivisibility of an atom was proved wrong: an atom can be further subdivided into protons, neutrons and electrons. ... According to Dalton, the atoms of same element are similar in all respects. However, atoms of some elements vary in their masses and densities. These atoms of different masses are called isotopes.

Answer:

Cl^- = 5.75

K^+ = 7.75

Explanation:

Now let us calculate the effective nuclear charge four K^+ and Cl^- from Slater's rule.

Given that Cl^- and K^+ has electronic configuration of; [Ne] 3s2 3p6 (they are isoelectronic species)

We compute S as follows;

For n - 2 level, S= 1

For n - 1 level, S= 0.85

For ns,np level S= 0.35

Note: S= screening or shielding constant

1s2, S=2 ×1 = 2

2s2 2p6, S= 8×0.85 = 6.8

3s2 3p6, S= 7 × 0.35 = 2.45

The electron under study is not considered hence seven out of eight electrons in the shell are considered

Hence

S= 2 + 6.8 + 2.45 = 11.25

Since Cl^- has 17 electrons;

Zeff(Cl^-) = 17 - 11.25 = 5.75

For K^+

Zeff = 19 - 11.25 = 7.75

Answer:

compound

Explanation:

Answer:

Explanation:

Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. ... Gravity creates stars and planets by pulling together the material from which they are made. Gravity not only pulls on mass but also on light.

Answer:

The goal of science is to learn how nature works by observing the natural and physical world, and to understand this world through research and experimentation.

Explanation:

Answer:If you help me with the triple beam balance gizmo then i can do this for you

Explanation:please i need help

Answer:

compound

Explanation:

Answer:

your answer would be compound

Answer:

The activation energy for the forward reaction is the amount of free energy that must be added to go from the energy level of the reactants to the energy level of the transition state. ... Once a reactant molecule absorbs enough energy to reach the transition state, it can proceed through the remainder of the reaction.

Explanation:

Answer: Activation energy is how much energy it takes for a reaction to occur.

Explanation:

Answer:

I think its a and c

Explanation:

im smrt

as distance from nucleus increases , energy of shells also increases

Answer:

Follows are the solution:

Explanation:

A + B = C

Its response decreases over time as well as consumption of a reactants.  

r = -kAB

during response A convert into 2x while B convert into x to form 3x of C

let's  y = C

y = 3x

Still not converted sum of reaction  

for A: 100 - 2x

for B: 50 - x

Shift of x over time  

[tex]\frac{dx}{dt} = \frac{-k(100 - 2x)}{(50 - x)}[/tex]

Integration of x as regards t  

[tex]\frac{1}{[(100 - 2x)(50 - x)]} dx = -k dt\\\\\frac{1}{2[(50 - x)(50 - x)]} dx = -k dt\\\\\ integral\ \frac{1}{2[(50 - x)^2]} dx =\ integral [-k ] \ dt\\\\\frac{-1}{[100-2x]} = -kt + D \\\\[/tex]

D is the constant of integration

initial conditions: t = 0, x = 0

[tex]\frac{-1}{[100-2x]} = -kt + D \\\\\frac{ -1}{[100]} = 0 + D\\\\D= \frac{-1}{100}\\\\[/tex]

hence we get:

[tex]\frac{-1}{[100-2x]}= -kt -\frac{1}{100}\\\\or \\\\ \frac{1}{(100-2x)} = kt + \frac{1}{100}[/tex]

after t = 7 minutes , [tex]C = 10 \ g = 3x[/tex]

[tex]3x = 10\\\\x = \frac{10}{3}[/tex]

Insert the above value x into [tex]\frac{1}{(100-2x)}[/tex] equation [tex]= kt + \frac{1}{100}[/tex] to get k.  

[tex]\to \frac{1}{(100-2\times \frac{10}{3})} = k \times (7) + \frac{1}{100} \\\\ \to \frac{1}{(100- 2 \times 3.33)} = \frac{700k + 1}{100} \\\\ \to \frac{1}{(100-6.66)} = \frac{700k + 1}{100}\\\\ \to \frac{1}{93.34} = \frac{700k + 1}{100} \\\\[/tex]

[tex]\to 100 = 93.34(700k + 1) \\\\ \to 100 = 65,338k + 700 \\\\ \to 65,338k = -600 \\\\ \to k = \frac{-600}{ 65,338} \\\\ \to k= - 0.0091[/tex]

therefore plugging in the equation the above value of k  

[tex]\to \frac{1}{(100-2x)} = kt +\frac{1}{100} \\\\\to \frac{1}{(100-2x)} = -0.0091t + \frac{1}{100}\\\\\to \frac{1}{(100-2x)} = \frac{1 -0.91t}{100}\\\\\to \frac{1}{2(50-x)} = \frac{1 -0.91t}{100}\\\\\to \frac{1}{(50-x)} = \frac{1 -0.91t}{50}\\\\\to 50= (1-0.91t)(50-x)\\\\\to 50 = 50-45.5t-x-0.91tx\\\\\to x+0.91xt= -45.5t\\\\\to x(1+0.91t)= -45.5t\\\\\to x=\frac{-45.5t}{1+0.91t}[/tex]

Let y = C

, calculate C:

y = 3x

[tex]y =3 \times \frac{-45.5t}{1+0.91t}[/tex]

amount of C formed in 28 mins

[tex]x = \frac{-45.5t}{1+0.91t} ,[/tex] plug t = 28

[tex]\to x = \frac{-1274}{1+25.48} \\\\\to x = \frac{-1274}{26.48} \\\\\to x= -48.26[/tex]

therefore amount of C formed in 28 minutes is = 3x = 144.78 grams

C: [tex]y =3 \times \frac{-45.5t}{1+0.91t}[/tex]

y= 136.5 =137

Explanation:

NH₃ has only two non-binding pairs (lone pairs) of e⁻ in it's Lewis structure.

••

H—N—H

|

H

Therefore,

C is correct. ✔

Answer:

The expression of speed of light can be written as "c".

Explanation:

The speed of light is denoted by c. It is originated from the Latin word celeritas which means "speed".  Its value is 3×10⁸ m/s.

It is related to the frequency and wavelength as follow,

Speed of light = wavelength × frequency

c = λ × f

λ = c/f

This formula shows that both frequency ad wavelength are inversely related to each other.

Frequency is taken in Hz.

It is the number of oscillations, wave of light make in one second.

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

Answer:

1.) Genetic Variation, 2.) reproduction doesn't require a mate.

Explanation:

These are the only two that actually make sense in the blanks, So trust me or trust the other two answers.Your choice.