please help..............

Answer:

[tex]4.86\times10^{-7}\ \text{m}[/tex]

Explanation:

R = Rydberg constant = [tex]1.09677583\times 10^7\ \text{m}^{-1}[/tex]

[tex]n_1[/tex] = Principal quantum number of an energy level = 2

[tex]n_2[/tex] = Principal quantum number of an energy level for the atomic electron transition = 4

Wavelength is given by the Rydberg formula

[tex]\lambda^{-1}=R\left(\dfrac{1}{n_1^2}-\dfrac{1}{n_2^2}\right)\\\Rightarrow \lambda^{-1}=1.09677583\times 10^7\left(\dfrac{1}{2^2}-\dfrac{1}{4^2}\right)\\\Rightarrow \lambda=\left(1.09677583\times 10^7\left(\dfrac{1}{2^2}-\dfrac{1}{4^2}\right)\right)^{-1}\\\Rightarrow \lambda=4.86\times10^{-7}\ \text{m}[/tex]

The wavelength of the light emitted is [tex]4.86\times10^{-7}\ \text{m}[/tex].

Answer:

a chemical change

Explanation:

lighting a match is a chemical change. chemical reactions cause chemical change. in a chemical reaction two or more substances, called the reactants, form different substances called products. hope this helped :)

Answer: metal and salt water

Explanation: salt starts to brake down metal and metal is everywhere in the ocean hope this helps

Answer:

baking a cake.

Explanation:

baking a cake is an example of a chemical reaction that happens daily because a new substance is forming when the cake is being baked. hope this helps! :)

Answer:

[tex]c=0.2\ J/g^{\circ} C[/tex]

Explanation:

Given that,

Mass of a glass, m = 4 g

Initial temperature, [tex]T_i=5^{\circ} C[/tex]

Final temperature, [tex]T_f=45^{\circ} C[/tex]

Heat absorbed, Q = 32 J

We need to find the specific heat of the glass. The formula for the heat absorbed is given by :

[tex]Q=mc\Delta T\\\\c=\dfrac{Q}{m\Delta T}\\\\c=\dfrac{32\ J}{4\ g\times (45-5)^{\circ} C}\\\\=0.2\ J/g^{\circ} C[/tex]

So, the required specific heat of the glass is [tex]0.2\ J/g^{\circ} C[/tex].

Answer:

None have backbones

No cell walls

Multicellular

Includes radial or bilateral body symmetry.

Explanation:

Answer:

[tex]PNCl_2[/tex]

Explanation:

Hello!

In this case, when determining empirical formulas by knowing the by-mass percent, we first must assume the percentages as masses so we can compute the moles of each element:

[tex]n_P=\frac{26.73g}{30.97g/mol}=0.863mol\\\\n_N=\frac{12.09g}{14.01g/mol}=0.863mol\\\\n_C_l=\frac{61.18g}{35.45g/mol}=1.726mol[/tex]

Now, for the determination of the subscript of each element in the empirical formula, we divide the moles by the fewest moles (P or N):

[tex]P=\frac{0.863mol}{0.863mol}=1\\\\N= \frac{0.863mol}{0.863mol}=1\\\\Cl=\frac{1.726mol}{0.863mol}2[/tex]

Thus, the empirical formula is:

[tex]PNCl_2[/tex]

Regards!

Answer:

[tex]c=0.127\ J/g^{\circ} C[/tex]

Explanation:

Given that,

Mass of the sample, m = 275 g

It required 10.75 kJ of heat to change its temperature from 21.2 °C to its melting temperature, 327.5 °C.

We need to find the specific heat of the metal. The heat required by a metal sample is given by :

[tex]Q=mc\Delta T[/tex]

c is specific heat of the metal

[tex]c=\dfrac{Q}{m\Delta T}\\\\c=\dfrac{10.75\times 10^3\ J}{275\times (327.5 -21.2)}\\\\=0.127\ J/g^{\circ} C[/tex]

So, the specific heat of metal is [tex]0.127\ J/g^{\circ} C[/tex].

Answer:

The relationship is the "variation of vapour pressure with temperature" or " the effect of vapour pressure on the melting and boiling points in a phase"

Answer:

they have a fixed pair of magnets and a rolling coil they convert motion into electric energy they are powered by fosile fuels they use reletive motion of a magnet and coil of a wire

Explanation:

Answer:

They convert motion energy to electric energy.

They use the relative motion of a magnet and a coil of wire.

Explanation:

This is the correct answer.

Identify the type of solid from the description. Select from the following choices: metallic solid, network solid, molecular solid, ionic solid, or amorphous solid. a. This solid is ductile and conducts electricity.b. This solid is not conductive and has a low melting point.

Answer:

See explanation

Explanation:

A is a Metallic Solid

Let us look again at the physical properties of metals;

Metals are

We can now see that both ductility and electrical conductivity are metallic properties.

B is a Molecular solid

Molecules are formed when atoms share electrons. In molecules, there are no free electrons hence molecules do not conduct electricity.

Secondly, molecules are held together in the solid state by weak dispersion forces hence molecular solids have a low melting point.

Answer:

Because the compound has a formula of M2O, the number of valence electrons of M should be 1. Therefore, (1) Group 1 is the correct answer because elements in group 1 have 1 valence electron.

Explanation:

Answer:

1) An area's long term weather pattern

Explanation:

Climate is defined as the weather pattern in an area for the long term. Climate means the usual condition of the humidity, temperature, wind, rainfall, and atmospheric pressure in the surface area of Earth for the long term. Usually the time period for a climate in a region is taken over 30-years.

Weather is the state of the atmosphere and climate the long-term weather pattern of the area. For example: degree to which it is hot or cold is weather and expect snow in the Northeast in every January is climate.

Hence, the correct answer is "1) An area's long term weather pattern".

Answer: Food webs are made of many food chains is the answer.

Explanation:

Food web consists many food chains.

The balance chemical equation is 2LiOH + CO2 → Li2CO3 + H2O. Therefore, option A is correct.

A chemical equation is said to be balanced if the quantity of each type of atom in the reaction is the same on both the reactant and product sides. In a balanced chemical equation, the mass and the change are both equal.

The law of conservation of mass states that when a chemical reaction takes place, the mass of the reactants and products should be equal. As a result, during the chemical process, the number of atoms in each element remains constant. The chemical equation must be balanced as a result.

The chemical equation is said to be balanced if there are no inequalities. Every element in this illustration now has the same amount of atoms on the reactant and product sides.

Thus, option A is correct.

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Answer:

Theory- 1 to 7

Explanation:

Exercise- 8 to 25

ect

The right alternative is Option D (0.78 V).

According to the question,

By putting the values, we get

Cu+2 + 2e → Cu E = 0.52 V

Ag+1 + 1e Ag E° = 0.78 V

= 1.23 - 0.45

= 0.78.

negative

The standard cell potential is quite negative, so the reaction will not occur spontaneously as written.

Missing parts of the question.

Using the two cell reduction potentials shown for their corresponding reaction, calculate the cell potential for a voltaic cell made from these two systems: 0.78.

Cu+2 + 2e → Cu E = 0.52 V

Ag+1 + 1e Ag E° = 0.80 V

options:

A)

0.28 V

B)

–1.32 V

C)

1.32 V

D)

–0.28 V

Learn more about cell potential at

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Answer:false

Explanation:

The solubility of lead chromate : s= 5.29 x 10⁻⁷ mol/L

Given

Ksp  for PbCl,=2.8x10*-13 mole/dmº

PbCrO4

Required

The solubility

Solution

P b C r O ₄ ( s ) ⇌ P b²⁺( a q) +C r O ₄ ⁻²( a q )

s                     s               s

s= solubility

Ksp P b C r O ₄  = s²

K s p  = [ P b ²⁺] [C r O ₄ ⁻² ]= 2.8x10⁻¹³

s = √2.8x10⁻¹³

s= 5.29 x 10⁻⁷ mol/L

Answer:

36 electrons

Explanation:

The # of protons is always equal to the atomic number. In the case of Sr (Strontium), it is 38 protons.

The 2+ at the end means that it has a charge of +2, meaning that it LOST two electrons to become a cation with a full valence shell. So, 38 - 2 = 36 electrons

Answer:

38 protons 36 electrons 30 neutron because of 29 isotope

Answer:

The coefficient of Z₂ is 1.

Explanation:

From the question given above:

X + ZY —> XY + Z₂

Next, we shall balance the equation to obtain the coefficient of Z₂. This can be obtained as follow:

X + ZY —> XY + Z₂

There is 1 atom of Z on the left side and 2 atoms on the right side. It can be balance by putting 2 in front of ZY as shown below:

X + 2ZY —> XY + Z₂

There are 2 atoms of Y on the left side and 1 atom on the right side. It can be balance by putting 2 in front of XY as shown below:

X + 2ZY —> 2XY + Z₂

Now, we have 1 atom of X on the left side and 2 atoms on the right side. It can be balance by putting 2 in front of X as shown below:

2X + 2ZY —> 2XY + Z₂

Now the equation is balanced.

Thus, the coefficient of Z₂ is 1.

Answer:

Slide a magnet through the mixture. When you take the magnet off, the iron filings are going to be attracted to the magnet and the sand will stay in the bowl

Explanation:

Answer:

Density can be used to separate the substances that make up a mixture, because each substance in a mixture has its own density.  For example, if a mixture of sand and oil is placed in water, the sand will sink to the bottom of the container. The sand is more dense than the water.

Explanation:

Please mark me as brainy if this helps

Answer:

Non polar covlant

Explanation:

Answer:

They are all mixture

Explanation:

last option

Answer: Alloy

Explanation: gold is an alloy, or mixture of metals

The answer is A. The vibration caused by the waves through the air eventually weaken, which is why sound diminishes easily over distance.

Answer:

D. Oxidation

Explanation:

In an electrolytic cell, oxidation (the loss of electrons) takes place at the anode. At the cathode reduction takes place.

A mnemonic technique that could be used is that the process that starts with a vowel (Oxidation) takes place at the place that also starts with a vowel (Anode).

Answer:

6200 meters

Explanation:

To convert from km to m you have to multiply the number by a thousand

Answer:

6.2×10^3 m

Explanation:

6.20×1000=6200m

In scientific notation 6200 = 6.2×10^3