please help tq !! A B C or D ?????

Answer:

B

Explanation:

I’m not really great at chemistry but I truly tried my best

Answer: Yes, the student is right, one should use pellets of the reactant should be heated and stirred for mixing properly.

Explanation:

In case of smaller particles the surface area that is being exposed increases and the due to this the reaction occurs faster.

Increasing the temperature of the temperature, increases the kinetic energy of the particles which helps in easy mixing of the particles.

The collision in between the particles also increase while stirring and thus the rate of reaction increases.

So, the heating and stirring is more preferred over powered reactant for making a solution quickly.

Answer:

false

Explanation:

Answer:

500

Explanation:

Answer:

Full moon.

Explanation:

This diagram shows a full moon because the sunlight is shining directly onto the side of the moon facing the earth in this instance.

Answer:

It is A

Explanation:

Answer:

I has 5 valance electrons it wants 10 and 3 bonds

Explanation:

Answer: 305 g of [tex]Be_3(PO_4)_2[/tex] will be produced from 38 grams  of beryllium oxide

Explanation:

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]    

[tex]\text{Moles of} BeO=\frac{38g}{25g/mol}=1.52moles[/tex]

[tex]3BeO+2FePO_4\rightarrow Be_3(PO_4)_2+Fe_2O_3[/tex]

According to stoichiometry :

3 moles of [tex]BeO[/tex] produce = 1 mole of [tex]Be_3(PO_4)_2[/tex]

Thus 1.52 moles of [tex]BeO[/tex] will produce =[tex]\frac{1}{3}\times 1.52=0.507moles[/tex]  of [tex]Be_3(PO_4)_2[/tex]

Mass of [tex]Be_3(PO_4)_2=moles\times {\text {Molar mass}}=0.507moles\times 602g/mol=305g[/tex]

Thus 305 g of [tex]Be_3(PO_4)_2[/tex] will be produced from 38 grams  of beryllium oxide

Answer:

The new temperature is 200 K.

Explanation:

Charles law gives the relationship between temperature and volume of a gas. It states that volume is directly proportional to temperature such that,

[tex]V\propto T\\\\\dfrac{V_1}{V_2}=\dfrac{T_1}{T_2}[/tex]

We have,

[tex]T_1=100\ K\\\\V_1=500\ mL\\\\V_2=1000\ mL\\\\T_2=?[/tex]

Plugging all the values,

[tex]T_2=\dfrac{V_2T_1}{V_1}\\\\T_2=\dfrac{1000\times 100}{500}\\\\T_2=200\ K[/tex]

So, the new temperature is 200 K.

Answer:

Heating the CuSO4. 5H2O crystals causes then to loose the water of crystallisation that is the 5H2O part. It becomes anhydrous copper sulphate. Its colour changes to white from blue.

Answer:

THE NEW VOLUME OF THE GAS SAMPLE IS 40 L AT 1 atm AND 400 K

Explanation:

Using general gas equation which combines Boyle's and Charles' law, the volume of the gas sample at the new pressure and temperature can be obtained.

P1V1/T1 = P2V2/T2

P1 = Initial pressure = 2 atm

V1 = Initial volume = 15 L

T1 = Initial temperature = 300 K

P2 = Final pressure = 1 atm

T2 = Final temperature = 400 K

V2 = Final volume = unknown

Substituting the values into the equation, we have;

V2 = P1V1T2 / P2 T1

V2 = 2 * 15 * 400 / 1 * 300

V2 = 12 000/ 300

V2 = 40 L

The new volume after the pressure was reduced to 1 atm and the temperature increased to 400 K is 40 L.

Answer: 1. [tex]NH_3[/tex] increases.

Explanation:

Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

For the given equation:

[tex]N_2(g)+3H_2(g)\rightleftharpoons 2NH_3(g)+energy[/tex]

If the concentration of [tex]N_2[/tex] is increased , according to the Le-Chatlier's principle, the reaction has to shift to right or forward direction. In order to do that  the concentration of products has to increase.

Thus the concentration of [tex]NH_3[/tex] increases.

1107 Joule is the amount of energy which is needed to change 88.0 g of solid benzene at 5.53°C into liquid benzene, also at 5.53°C.

In order to perform work and to produce heat and light, energy must be delivered to a body or to an external physical system. Energy is a quantitative property. Energy is a preserved resource; according to the rule of conservation of energy, energy can only be transformed from one form to another and cannot be created or destroyed. 

A moving object's kinetic energy, an object's potential energy, an object's elastic energy, chemical energy linked to chemical reactions, electromagnetic radiation's radiant energy, and the internal energy of a thermodynamic system are examples of common kinds of energy.

mole of benzene = 85.2/78.11 =1.09mol

1 mole of benzene requires  10.19 kJ/mol energy

1.09 mole of benzene requires 1.09× 10.19 kJ/mol = 11.107kJ/mol energy

                                                                                  = 1107 Joule energy

Therefore,  1107 Joule is the amount of energy which is needed to change 88.0 g of solid benzene at 5.53°C into liquid benzene, also at 5.53°C.

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a mushroom

Explanation:

it don't make sense because the tree is not food chain

Answer:

they are both primary producers so i would say they are at the same level, hope this helps

Answer:

The increase in mass is not due to the heating but due to the reaction of the metal with oxygen in air to form an oxide

Explanation:

When a metal is heated in the presence of air, oxygen present in air reacts with the metal to form the oxide of the metal. The mass of this oxide is greater than the original metal by the amount of oxygen added to the metal during the reaction.

The above reaction is known as an oxidation reaction. Generally,

metal M + O2 ---> MO2

Answer:

Option a. = 0.01 M

Explanation:

To do this, we need to gather the data:

E = 2.21 V

[Cl⁻] = 0.1 M

And the Redox reaction taking place is the following:

Zn(s) + Cl₂(g) <-------> Zn²⁺(aq) + 2Cl⁻(aq)       Q = [Zn] [Cl]²

E° Cl⁻/Cl₂ = 1.36 V

E° Zn/Zn²⁺ = -0.76 V

According to this, the expression to use will be the Nernst equation, and we can assume we are working at 25 °C, therefore, the Nernst equation will be:

E = E° - (0.059/n) logQ

E = E° - (0.059/n) ln([Cl⁻]² * [Zn²⁺])   (1)

From there, we can solve for Zn later.

First, we need to write the semi equation of oxidation and reduction, and get the standard potential of the cell:

Zn(s) --------> Zn²⁺(aq) + 2e⁻       E₁° = 0.76 V

Cl₂(g) + 2e⁻ -----------> 2Cl⁻(aq)   E₂° = 1.36 V

---------------------------------------------------------------

Zn(s) + Cl₂(g) -------> Zn²⁺(aq) + 2Cl⁻(aq)    E° = 0.76 + 1.36 = 2.12 V

Now, let's replace in (1) and then, solve for [Zn]:

2.21 = 2.12 - (0.059/2) log ([0.1]² * [Zn])

2.21 - 2.12 = -0.0295 log (0.01[Zn])

- 0.09 / 0.0295 = log (0.01[Zn])

-3.0508 = log (0.01[Zn])

10^(-3.0508) = 0.01[Zn]

8.8961x10⁻⁴ = 0.01[Zn]

[Zn²⁺] = 0.08896 M

This value can be rounded to 0.1 M. so the correct option will be option A.

Answer:

10.28 mol

Explanation:

S + 2O = SO2

(atm x L) ÷ (0.0821 x K)

(3.45 x 45.6) ÷ (0.0821 x 373)

=5.13726

Then round it to significant figures

=5.14

5.14 mol SO2 x (2 mol O ÷ 1 mol SO2)

=10.28 mol O

The number of moles of oxygen atoms in 5.14 moles of SO₂ gas is equal to 10.28 mol.

The ideal gas law is used to describe an equation of the state of an ideal gas. The ideal gas equation can be defined as the product of the volume (V) and the pressure (P) of 1-mole ideal gas is equal to the product of the universal gas constant (R) and absolute temperature.

The ideal gas equation can be expressed in the mathematical form as follows:

PV = nRT

Where n is the moles of a gas, P is the pressure,  V is the volume of the gas,  and R is the universal gas constant.

Given, the volume of sulfur dioxide, V = 45.6 L

The temperature of SO₂ gas, T = 373 K

The universal gas constant, R =0.082 atmL /K mol

The pressure of the SO₂ gas, P = 3.45 atm

Substituting the values R, V, P, and T in the gas law equation, we get:

The number of moles of sulphur dioxide, n = PV/RT

n = 3.45 ×45.6/(0.082 × 373)

n = 5.14 mol

The number of moles SO₂ gas = 5.14

Moles of oxygen atoms in 5.14 moles of SO₂ = 2 × 5.14 = 10.28 mol

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Answer:

Silver (Ag)

Explanation:

The electronic configuration of copper is shown below;

[Kr]4d10 5s1

We can see that there is only one 5s1 electron. Hence Ag^+ tends to display a pseudo noble gas configuration. This pseudo noble gas configuration explains why silver is prevalent in the +1 oxidation state.

The other transition metals have many stable oxidation states found in nature. Chromium is observed both in +3 and +6 oxidation states. Iron is found in +2 and +3 oxidation states and copper is mostly stable in the +2 oxidation state since the +1 oxidation state readily disproportionate.

Hence silver tends to have only a single ionic charge for reasons aptly stated above.

Answer:7

Explanation:

H+ concentration of solutions is related to pH as -

[H+] = antilog(-pH)

For pH = 4,

[H+] = antilog(-4)

[H+] = 10^-4 M

For pH = 10,

[H+] = antilog(-10)

[H+] = 10^-10 M

When these 2 solutions are added, concentration of the mixture will be -

[H+] = √(10^-10 × 10^-4)

[H+] = √(10^-14)

[H+] = 10^-7 M

So now, pH of the mixture will be

pH = -log(10^-7)

pH = 7

Answer:

N2+O2-> 2NO

Explanation:

An endothermic reaction refers to a reaction in which heat taken in. This implies that heat is usually absorbed by the reaction system. The enthalpy of reaction for an endothermic reaction is always positive.

The triple bond between two Nitrogen atoms in N2 gas is very strong due to its small size and the triple bond thus the nitrogen molecule has a high dissociation energy. This accounts for the large amount of energy required to break the triple bond between nitrogen atoms in the nitrogen molecule. This causes the oxidation of Nitrogen molecule to NO to be largely endothermic.

Answer:

62,790J

Explanation:

Q=mcT

= 250g*4.186J/gc*80-20

=250*4.186*60=62,790J

Answer:

1.

2.

Explanation:

Protons and neutrons are located at the center of an atom which is nucleus .

Electrons will orbit around the nucleus .

Answer:

601mmHg.

Explanation:

Step 1:

Data obtained from the question.

Initial pressure (P1) = 760mmHg

Initial temperature (T1) = 100°C = 100°C + 273 = 373K

Final temperature (T2) = 22°C = 22°C + 273 = 295K

Final pressure (P2) =..?

Step 2:

Determination of the new pressure at which the water will boil.

The new pressure on the at which the water will boil can be obtained as follow:

P1/T1 = P2/T2

760/373 = P2/295

Cross multiply to express in linear form

373 x P2 = 760 x 295

Divide both side by 373

P2 = (760 x 295) / 373

P2 = 601mmHg

Therefore, the new pressure at which the water will boil is approximately 601mmHg.

Answer:

C. 18-20 mm

Explanation:

Answer:

Chemical change

Explanation:

Rust cannot be done without using chemicals.

Answer:

Option B.) Chemical Change

Answer:

0 being the lowist 14 being the hieist 0 is the most acidic 14 is the hieist base 7 is nutrol

Explanation:

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

How compact a certain object or person is

Answer:

Density is a measure of mass per unit of volume.The average density of an object equal its total mass divided by its total volume.

Answer: the line Spectra of hydrogen lies between the ultra-violet, visible light and infra-red of the electro magnetic spectrum

Explanation:

Electromagnetic radiation spans an wide range of wavelengths and frequencies. This range is called the electromagnetic spectrum. The electromagnetic spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency. The 7 regions includes; radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays.

lower-energy radiation, such as radio waves, is expressed as frequency while microwaves, infrared, visible and UV light are usually expressed as wavelength and finally, higher-energy radiation such as X-rays and gamma rays, is expressed in terms of energy per photon.

Therefore, hydrogen lies between the ultra-violet, visible light and infra-red region of the electro magnetic spectrum.

Answer:

Explanation:

SO; If we assume that:

P should be the diffusion of oxygen towards the surface ; &

Q should be the  diffusion of carbondioxide away from the surface.

Then  the total molar flux of oxygen is illustrated by :

[tex]Na,x = - cD_{PQ}\frac{dy_P}{dr} +y_P(NP,x + N_Q,x)[/tex]

where;

r is the radial distance from the center of the carbon particle.

Since ;

[tex]N_P,x = - N_Q, x[/tex] ; we have:

[tex]Na,x = - cD_{PQ}\frac{dy_P}{dr}[/tex]

The system is not steady state and the molar flux is not independent of r because the area of mass transfer [tex]4\pi r^{2}[/tex] is not a constant term.

Therefore,  using quasi steady state assumption, the mass transfer rate   [tex]4\pi r^{2}N_{P,x}[/tex] is assumed to be independent of r at any instant of time.

[tex]W_{P}=4\pi r^{2}N_{P,x}[/tex]

[tex]W_{P}=-4\pi r^{2}cD_{PQ}\frac{dy_{P}}{dr}[/tex]        

       = constant

The oxygen concentration at the surface of the coal particle [tex]yP,R[/tex] will be calculated from the reaction at the surface.

The mole fraction of oxygen at a location far from pellet is 1.

Thus, separating the variables and integrating result into  the following:

[tex]W_{P}\int_{R}^{\infty} \frac{dr}{r^{2}}=-4\pi[/tex]

[tex]r^{2}cD_{PQ}\int_{y_{P,R}}^{y_{P,\infty }}dy_{P}[/tex]

[tex]-W_{P}\frac{1}{r}\mid ^{\infty }_{R}= -4\pi cD_{PQ}(y_{P,\infty }-y_{P,R})[/tex]

[tex]=> W_{P}= - 4\pi cD_{PQ}(1-y_{P,R})R[/tex]

The mole of oxygen arrived at the carbon surface is equal to the mole of oxygen consumed by the chemical reaction.

[tex]W_{P} = 4 \pi R^2R"[/tex]

[tex]W_{P}= 4\pi R^{2}k_{1}"C_{O_{2}}\mid _{R}[/tex]

[tex]W_{P}= 4\pi R^{2}k_{1}"c y _{P,R}[/tex]

[tex]-4\pi cD_{PQ}(1-y_{P,R})R= - 4\pi R^{2}k_{1}"c y _{P,R}[/tex]

[tex]y_{P,R}=\frac{D_{PQ}}{D_{PQ}+Rk_{1}}[/tex]

[tex]y_{P,R}=\frac{1.7 \times 10^{-4}}{1.7\times 10^{-4}+10^{-3}\times 0.1}[/tex]

[tex]\mathbf{= 0.631}[/tex]

Obtaining the total gas concentration from the ideal gas law; we have the following:

where;

R= [tex]0.082m^3atm/kmolK[/tex]

[tex]c=\frac{P}{RT} \\ \\ c=\frac{1}{0.082\times 1450} \\ \\ = 0.008405kmol/m^3[/tex]

The steady state [tex]O_2[/tex] molar consumption rate is:

[tex]W_{P}= -4\pi cD_{PQ}(1-y_{P,R})R[/tex]

[tex]W_{P}= -4\pi (0.008405)(1.7\times 10^{-4})(1-0.631)(10^{-3})[/tex]

[tex]W_{P}= - 6.66\times 10^{-9}kmol/s[/tex]

Answer:

[tex]3 Mg(s) + N_2(g) = Mg_3N_2(s)[/tex]

Explanation:

The valance of magnesium atom is  [tex]+2[/tex]

While the valence of nitrogen atom is [tex]- 3[/tex]

Let us first write the first  half-reactions

[tex]Mg ---> Mg^{2+} + 2e^{-}[/tex]

The second half reaction is

[tex]2N + 6e^- -----> N_2[/tex]

Adding the above two reactions and writing the final reaction, we get -

[tex]Mg + N2 = Mg_3N_2[/tex]

The balance equation is

[tex]3 Mg(s) + N_2(g) = Mg_3N_2(s)[/tex]

Answer:  3597 kJ of heat

Explanation:

According to ideal gas equation:

[tex]PV=nRT[/tex]

P = pressure of gas = 5.00 atm

V = Volume of gas = 8.00 L

n = number of moles = ?

R = gas constant =[tex]0.0821Latm/Kmol[/tex]

T =temperature =[tex]25.0^0C=(25.0+273)K=298K[/tex]

[tex]n=\frac{PV}{RT}[/tex]

[tex]n=\frac{5.00atm\times 8.00L}{0.0821 L atm/K mol\times 298K}=1.63moles[/tex]

As it is given :

1 mole of propane produces = 2220 kJ of heat

Thus 1.63 moles of propane produces = [tex]\frac{2200}{1}\times 1.63=3597kJ[/tex]

Thus 3597 kJ of heat is produced