Can someone please help me

Answer:

c

Explanation:

Answer:

C.164.1g/mol

Explanation:

40+14×2+16×6

164

The molar mass of Ca(NO3)2 is 164.1 g/mol.

Calcium nitrate, also called Norgessalpeter (Norwegian salpeter), is an inorganic compound with the formula Ca(NO3)2(H2O)x. The anhydrous compound, which is rarely encountered, absorbs moisture from the air to give the tetrahydrate. Both anhydrous and hydrated forms are colourless salts. Calcium nitrate is mainly used as a component in fertilizers, but it has other applications. Nitrocalcite is the name for a mineral which is a hydrated calcium nitrate that forms as an efflorescence where manure contacts concrete or limestone in a dry environment as in stables or caverns. A variety of related salts are known including calcium ammonium nitrate decahydrate and calcium potassium nitrate decahydrate.

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Answer:

Yes you are correct

Explanation:

But the spelling is black amu

Answer: closed system

Explanation:

Answer: 2KClO3 → 2KCl + 3O2

Explanation: it's the only one that was broken down into more parts than the start, the rest were simply reseperated

this one : 1 → 2

b : 1 + 1 = 2

c : xy+ wz  → wy + xz

d : qwer +tyuio → qwui + tyero

ALSO I got it right

Answer:

option D

Explanation:

first quantum number of a 2s2

n = 2

second quantum number of a 2s2

l = 0 to n-1

l = 0, 1

For s orbital

l = 0

third quantum number of a 2s2

ml = - l to +l

ml = 0

fourth quantum number of a 2s2 electron be

?½ = spin down

½ = spin up

2s2 has 2 electrons 1 spin down and 1 spin up (starts with spin down)

ms = +1/2

Answer:

+1/2

Explanation:

Answer:

c

Explanation:

h

Answer:

0.64 moles of table salt = 37.44 grams of table salt

Explanation:

mNaCl = 0.64 x (23 + 35.5) = 37.44 grams

Answer:

pH → 7.47

Explanation:

Caffeine is a sort of amine, which is a weak base. Then, this pH should be higher than 7.

Caffeine + H₂O  ⇄  Caffeine⁺  +  OH⁻      Kb

1 mol of caffeine in water can give hydroxides and protonated caffeine.

We convert the concentration from mg/L to M

415 mg = 0.415 g

0.415 g / 194.19 g/mol = 2.14×10⁻³ mol

[Caffeine] = 2.14×10⁻³  M

Let's calculate pH. As we don't have Kb, we can obtain it from pKb.

- log Kb = pKb → 10^-pKb = Kb

10⁻¹⁰'⁴ = 3.98×10⁻¹¹

We go to equilibrium:

Caffeine + H₂O  ⇄  Caffeine⁺  +  OH⁻      Kb

Initially we have 2.14×10⁻³ moles of caffeine, so, after the equilibrium we may have (2.14×10⁻³ - x)

X will be the amount of protonated caffeine and OH⁻

     Caffeine     +    H₂O  ⇄  Caffeine⁺  +  OH⁻      Kb

   (2.14×10⁻³ - x)                         x                x

We make the expression for Kb:

3.98×10⁻¹¹ = x² / (2.14×10⁻³ - x)

We can missed the -x in denominator, because Kb it's a very small value.

So: 3.98×10⁻¹¹ = x² / 2.14×10⁻³

√(3.98×10⁻¹¹ . 2.14×10⁻³) = x → 2.92×10⁻⁷

That's the [OH⁻].  - log [OH⁻] = pOH

- log 2.92×10⁻⁷ = 6.53 → pOH

14 - pOH = pH → 14 - 6.53 = 7.47

Answer:

Thomson--atoms cotain electron

Ernest Rutherford--atoms have a positive nucleus

R.A Millikan--electrons have Q=-1

Dalton--atoms are indivisible

Millikan---> Electrons have a charge of -1

Rutherford ---> Atoms have a positive nucleus

Thomson -----> Atoms contain electrons

Dalton --------> Atoms are indivisible

The atomic theory went through several modifications and different scientists proposed various models of the atom until our present conception of the atom was developed.

The atom was first defined as the smallest indivisible particle of a substance. This idea of "indivisibility" of the atom stems from Dalton's theory.

The fact that atoms were composed of negatively charged electrons was proven by the experiments of J.J Thompson using the cathode ray tube. Millikan's charge to mass experiment showed that the electron has a charge of -1.

Rutherford, in his famous gold foil experiment showed that atoms were composed of a positively charged nucleus.

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Answer: The forces of attraction are stronger in new attractions that are formed.

Explanation:

When a chemical reaction takes place between two or more different compounds then less reactive substance is displaced by the more reactive substance.

During this process, when bonds are broken between the reactants then it means the force of attraction is less stronger. The formation of new compounds occur because force of attraction is more in these new substances due to which its atoms come closer to each other.

Thus, we can conclude that forces of attraction are stronger in new attractions that are formed.

Explanation:

first find the value of Ph

from Ph= -log[H+]

ph=-log[1.7x10^-8]=7.769

find Poh from 14=ph+poh

14=7.769+poh

Poh=6.231 part a

for part b the same as part a from the above procedure

Answer:

10km

Explanation:

Answer:

[tex]\boxed {\boxed {\sf 10 \ kilometers}}[/tex]

Explanation:

Distance is the product of speed and time.

[tex]d=s \times t[/tex]

The speed of the ship is 5 kilometers per hour. The time is 2 hours.

Substitute the values into the formula.

[tex]d= 5 \ km/hr * 2 \ hr[/tex]

Multiply. Note that the hours will cancel each other out.

[tex]d= 5 \ km * 2 \\d=10 \ km[/tex]

The ship covers a distance of 10 kilometers.

Answer:

convection

Explanation:

Convection is a mode of heat transfer in which the particles of a substance actually move from place to place.

During convection, warmer and less dense air rises while colder and denser air sinks downwards under gravity.

Hence; when hot air balloon rises because the fire warms up the air and the air circulates to fill the balloon and lift it at the same time, convection has taken place.

Answer:

B. Wind

Explanation:

Kinetic energy is moving

Answer:

C, hexanal

Explanation:

Option C is correct. The given name of the aldehyde CH3CH2CH2CH2CH2CHO is Hexanal

Aldehydes are organic compounds formed from the oxidation of alcohols. The contains the group -CHO

Given the compound CH3CH2CH2CH2CH2CHO

For us to name this compound, we need to first know:

Since there are 6 carbons in the chain, hence the alkane equivalent will be hexane.

Since it is an aldehyde compound.

General naming = alkane name + group name of aldehyde

compound name = alkane name + (-nal)

compound name = hexanal

Hence the name of the given aldehyde is Hexanal

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Answer:

The correct answer is the last option

Explanation:

Answer:rust

Explanation:

The gold is not the compound.

The information related to the compound is as follows

Therefore we can say that gold is not the compound.

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This is a Charles' Law problem: V1/T1 = V2/T2. As the temperature of a fixed mass of gas decreases at a constant pressure, the volume of the gas should also decrease proportionally. Here, we are given the new volume of the gas after cooling, and we want to determine to what temperature the gas was cooled.

To use Charles' Law, the temperature must be in Kelvin (x °C = x + 273.15 K). We want to solve Charles' Law for T2, which we can obtain by rearranging the equation into T2 = V2T1/V1. Given V1 = 130 L, T1 = 250 °C (523.15 K), and V2 = 85 L:

T2 = (85 L)(523.15 K)/(130 L) = 342 K or 68.9 °C. If sig figs are to be considered, since all the values in the question are given to two sig figs, the answer to two sig figs would be either 340 K or 69 °C.  

Gases show great uniformity in their behaviour irrespective of their nature. The concept Charles's law is used here to determine the new temperature of the gas. The new temperature of the gas is 341.96 K.

At constant pressure, the volume of a given mass of gas is directly proportional to the temperature on Kelvin scale. The absolute scale of temperature is introduced by the scientist Charles. The temperature at which gases supposed to have zero volume is called the absolute temperature.

Mathematically the Charles's law can be expressed as:

V = constant × T

V / T = constant

For two different gases, the equation is:

V₁ / T₁ = V₂ / T₂

T₂ = V₂T₁ / V₁

85 × 523 / 130 = 341.96 K

Thus the new temperature of the gas is 341.96 K.

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Answer:

C

Explanation:

The weeds will be replaced by woody shrubs and some small trees.

If the forest land is cleared, it is hard to construct a forest again. The cleared land will grow as grass land then if there is no constructions or buildings fills the land. Hence, option B is correct.

Forestation is the process of formation of forests and dense growth of trees and other kinds of plants. Forests are example of ecosystems and  wide variety of plant species and animals are living there.

Nowadays, deforestation is common for the selfish purposes of man to buildups their own amenities so that, many more plants and animals are on the edge of extinction.

There are naturally made forests as well as man made forests.  It was results of hard working that to form a forest with all its atmosphere and biodiversity will take longer time. It will not happen within just five years.

Thus,  if the forest land is cleared, the empty ground may fill with grasses and flower plants. Hence option B is correct.

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Answer:16

Explanation:

The balanced equation of the given reaction is as follows: 5SiO2 + 2CaC2 → 5Si + 2CaO + 4CO2.

A chemical equation is said to be balanced when the number of atoms of each element on both sides of the equation is the same.

According to this question, a chemical reaction between quartz and calcium chloride is given to produce silicon, calcium oxide and carbon dioxide.

The balanced equation that represents an equal number of atoms on both sides is as follows:

5SiO2 + 2CaC2 → 5Si + 2CaO + 4CO2

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Answer:

3 KOH(aq) + H3PO4(aq) = K3PO4(aq) + 3 H2O

Explanation:

Answer:

you multiply it by the other subscripts in the parenthesis.

Explanation:

Answer:

the answer is a because thermal energy is heat and the question said that is not a factor of thermal energy so A does not refer to heat

Answer:

44.8 L

Explanation:

Ideal Gas Equation -

i.e.,

PV = nRT

where,

P = pressure

V = volume

n = moles

R = universal gas constant

T = temperature

Using the information given in the question, Volume of the gas can be calculated -

P = 101.3 kPa

V = ?

n = 2.00 moles

R = 8.31

T = 0 degree C = 273.15 K

Using the above data, and putting the data in the respective formula -

PV = nRT

101.3 kPa * V = 2.00 moles * 8.31 * 273.15 K

V = 44.8 L

Hence, the volume of the given gas = 44.8 L