Please help quicklyy!!

Answer:

[tex]\large \boxed{\text{3. Na}}[/tex]

Explanation:

We can use oxidation numbers to decide which substance is reduced.  

[tex]\rm 2\stackrel{\hbox{0}}{\hbox{Na}} + 2\stackrel{\hbox{+1}}{\hbox{ H}_{2}}\stackrel{\hbox{-2}}{\hbox{O}}\longrightarrow \rm 2\stackrel{\hbox{+1}}{\hbox{Na}^{+}} + 2\stackrel{\hbox{-2}}{\hbox{O}}\stackrel{\hbox{+1}}{\hbox{H}^{-}} + \stackrel{\hbox{0}}{\hbox{H}_{2}}[/tex]

The oxidation number of Na changes from 0 in Na to +1 in Na⁺.

The oxidation number of H changes from +1 in H₂O to 0 in H₂.

[tex]\text{An increase in oxidation number is oxidation, so $\large \boxed{\textbf{Na}}$ is the substance oxidized.}[/tex]

1 and 4 are wrong because H₂ and Na⁺ are products.

2. is wrong because there is no H⁺ to be oxidized or reduced.

Answer:

b

Explanation:

edge 2021

According to the concept of conduction,heat  flows from faster molecules to slower molecules when they collide.

Conduction is defined as a process as a means of which heat is transferred from the hotter end of the body to it's cooler end.Heat flows spontaneously from a body which is hot to a body which is cold.

In the process of conduction,heat flow is within the body and through itself.In solids the conduction of heat is due to the vibrations and collisions of molecules .

There are 2 types of conduction:1) steady state conduction 2) transient conduction.According to the type of energy conduction is of three types:

1) heat conduction

2) electrical conduction

3)sound conduction

Heat is transferred from faster to slower molecules when they collide , thus the correct option is that heat flows from faster molecules to slower molecules when they collide.

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Answer:

B

Explanation:

Oxidation

Zn---> Zn2+ 2e

Reduction

Cu2+ + 2e ---->Cu

Answer:

e

Explanation:

Answer:

A      20

B      40

C      Ca

D      10

E       9

F      F

Explanation:

bromine is used to distinguish between saturated and unsaturated compounds. when bromine water is added to the unsaturated compound, bromine that added to the unsaturated compound and the red brown colour of bromine water is discharged.

Answer:

Neutron

Explanation:

Answer:

4. Copper(II) carbonate

5. Magnesium carbonate

Explanation:

Only Potassium carbonate, Sodium carbonate and Ammonium carbonate are soluble.

The rest of the carbonates are insoluble.

Answer:

It is a metaphorical line that divides the earth from north to south

Explanation:

Answer:

Explanation:

given amount of salt at time t is A(t)

initial amount of salt =300 gm =0.3kg

=>A(0)=0.3

rate of salt inflow =5*0.4= 2 kg/min

rate of salt out flow =5*A/(200)=A/40

rate of change of salt at time t , dA/dt= rate of salt inflow- ratew of salt outflow

[tex]dA/dt=2-(A/40)\\\\dA=2dt-(A/40)dt\\\\dA+(A/40)dt=2dt[/tex]

integrating factor

[tex]=e^{\int\limits (1/40) \, dt}[/tex]

integrating factor [tex]=e^{(1/40)t}[/tex]

multiply on both sides by  [tex]=e^{(1/40)t}[/tex]

[tex]dAe^{(1/40)t}+(A/40)e^{(1/40)t} dt =2e^{(1/40)t}t\\\\(Ae^{(1/40)t})=2e^{(1/40)t}t[/tex]

integrate on both sides

[tex]\int\limits(Ae^{(1/40)t})=\int\limits2e^{(1/40)t}dt\\\\(Ae^{(1/40)t})=2*40e^{(1/40)t}+C\\\\A=80+(C/e^{(1/40)t})\\\\A(0)=0.3\\\\0.3=80+(C/e^{(1/40)t}^*^0)\\\\0.3=80+(C/1)\\\\C=0.3-80\\\\C=-79.7\\\\A(t)=80-(79.7/e^{(1/40)t})[/tex]

b)

after long period of time means t - > ∞

[tex]{t \to \infty}\\\\ \lim_{t \to \infty} A_t \\\\ \lim_{t \to \infty} (80)-(79/{e^{(1/40)t}}\\\\=80-(0)\\\\=80[/tex]

Answer:

static friction: books on a desk and a parked car

kinetic friction: moving furniture and riding a bike

fluid friction: swimming and skydiving

Explanation:

Answer:

static friction:

kinetic friction:

fluid friction:

Answer:

9.53g

Explanation:

Given the following :

Density = 1.065g/mL

Volume of solution = 25.0mL

% of acetic acid =58%

Molar mass of CH3COOH = 60.05g/mol

Molar mass of Ca(OH)2 = 74.093g/mol

Reaction:

2CH3COOH + Ca(OH)2 ----> Ca(CH3Co2)2 +2H2O

Volume of solution × density × % of CH3COOH × (mole per molar mass CH3COOH) × (mole of Ca(OH)2 per mole of CH3COOH) × (molar mass of Ca(OH)2 per mole of Ca(OH)2)

25mL × (1.065/1) × (58/100) × (1 / 60.05) × (1 / 2) × (74.093 / 1)

25 × 1.065 × 0.58 × 0.0166527 × 0.5 × 74.093

= 9.526g

Answer:

The correct option is;

Waves that move through the Earth

Explanation:

In attempting to unravel the nature and arrangements of the rocks beneath the Earths surface, Geologist apply numerous methodologies including seismological field survey and analysis whereby the time of travel of natural (due to events such as earthquakes) or man made (during geological exploration) seismic wave are analysed to image the nature, composition and dynamism of the Earth's interior to find out the presence of geological faults or liquid layers as well as to predict the possible occurrence of future events within the Earth's crust in detail.

A type of evidence that geologists usually study is: B. waves that move through Earth.

Geology can be defined as the scientific study of the substances (both solid and liquid) and physical structure of planet Earth, including the processes through which they change over time.

A geologist refers to an expert or professional that studies geology. Some of the various type of evidence that geologists usually study are:

The different rock samples that are existing on the surface of planet Earth.

The mineral composition of the different layers of planet Earth.

The waves that move through planet Earth such as electromagnetic waves.

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Answer:

a colloid (heterogeneous mixture) that dispearses the particles intermediate in size.

Explanation:

Answer:

La cantidad de yodo en la muestra es 0.217 g

Explanation:

Los parámetros dados son;

Normalidad de la solución de Na₂S₂O₃ = 0.1 N

Volumen de la solución de Na₂S₂O₃ = 17.1 mL

Masa de muestra = 0.376 g

La ecuación de reacción química se da de la siguiente manera;

I₂ + 2Na₂S₂O₃ → 2 · NaI + Na₂S₄O₆

Por lo tanto, el número de moles de sodio por 1 mol de Na₂S₂O₃ en la reacción = 1 mol

Por lo tanto, la normalidad por mol = 1 M × 1 átomo de Na = 1 N

Por lo tanto, 0.1 N = 0.1 M

El número de moles de Na₂S₂O₃ en 17,1 ml de solución 0,1 M de Na₂S₂O₃ se da de la siguiente manera;

Número de moles de Na₂S₂O₃ = 17.1 / 1000 × 0.1 = 0.00171 moles

Lo que da;

Un mol de yodo, I₂, reacciona con dos moles de Na₂S₂O₃

Por lo tanto;

0,000855 moles de yodo, I₂, reaccionan con 0,00171 moles de Na₂S₂O₃

La masa molar de yodo = 253.8089 g / mol

La masa de yodo en la muestra = 253.8089 × 0.000855 = 0.217 g.

Answer: it’s halfway

into the circle, you would need it when trying to find the circumference

Explanation:

Radius is used to find the circumference of the circle or sphere.

A straight line extending from the centre of a circle or sphere to the circumference or surface: The radius of a circle is half the diameter.

To calculate the circumference of a circle, multiply the diameter of the circle with π (pi). The circumference can also be calculated by multiplying 2×radius by pi.

Hence, the radius is used to find the circumference of the circle or sphere.

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Dependent variables receive this name because, in an experiment, their values are studied under the supposition. The dependent variable is the cleanliness of the clothes.

It is something on which other elements depend. A test score, for instance, may be a dependent variable because it could vary based on a number of variables, including how much you studied, how much sleep you got the night before the test, and even how hungry you were.

A dependent variable is one that is altered as a result of the modification of an independent variable. Your independent variable "depends" on the outcome you're interested in measuring. Dependent variables are also referred to as: response elements (they respond to a change in another variable)

There are often two different sorts of variables in analytical health research. We anticipate that independent variables will have an impact on dependent variables.

Thus,The dependent variable is the cleanliness of the clothes.

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Answer:

About 164 grams

Explanation:

The molecular formula of calcium nitrate is [tex]Ca(NO_3)_2[/tex]. The molar mass of calcium is about 40, while the molar mass of nitrogen is about 14 and oxygen is about 16. Therefore, the molar mass of it is:

[tex]40+2(14+3(16))=40+2(14+48)=40+124=164[/tex]

Hope this helps!

Answer:

B Nacl is a correct

Explanation:

Nacl is a correct

Answer:

2 mole of Sodium hydroxide reacts with 1 mole of Sulfuric acid

Explanation:

Write down the equation in the beginning with reactants and products:

NaOH + H₂SO₄ → Na₂SO₄ + H₂0

Now try to balance it. Try with Na first:

2NaOH + H₂SO₄ → Na₂SO₄ + H₂0

Na atoms are balanced. There are 6 Oxygen atoms on the right and 5 on the left. Balance by increasing the H₂O moles:

2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂0

Check if H atoms are also balanced. They are. That means our final reaction is:

2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂0

2 Moles of NaOH reacts with 1 mole of H₂SO₄

The moles of sodium hydroxide required to neutralize 1 mole of sulfuric acid have been 2 mol.

The balanced chemical equation for the titration of sodium hydroxide against sulfuric acid has been:

[tex]\rm 2\;NaOH\;+\;H_2SO_4\;\rightarrow\;Na_2SO_4\;+\;2\;H_2O[/tex]

From the balanced chemical equation, for the titration of 1 mole of sulfuric acid, 2 moles of sodium hydroxide has been required.

The moles of sodium hydroxide required for the titration of sulfuric acid has been:

[tex]\rm 1\;mol\;H_2SO_4=2\;mol\;NaOH[/tex]

Thus, the neutralization of 1 mole of sulfuric acid has been required 2 mol of sodium hydroxide.

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Answer:

Explanation:

Astronomers define star brightness in terms of apparent magnitude. How bright the star appears from Earth and absolute magnitude is how bright the star appears at a standard distance of 32.6 light-years, or 10 parsecs. (A light-year is the distance light travels in one year is about 6 trillion miles, or 10 trillion kilo meters.) Astronomers also measure luminosity, the amount of energy (light) that a star emits from its surface.

Distance of a light year = 3600 x 24 x 365.25 x 3 x [tex]10^{5}[/tex] ≅ 10 trillion kilo meters

Answer:

apparent

Explanation:

The brightness of a star as seen from Earth is referred to as

apparent brightness.

The plastic straws were placed under the wooden block to increase the surface area of the ramp. Hence, option C is correct.

Surface area is the measure of how much exposed area a solid object has expressed in square units.

The plastic straws were placed under the wooden block to increase the surface area of the ramp because putting straws will increase the area which has cylindrical hollow space inside the straw.

Hence, option C is correct.

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Answer:

10

Explanation:

Answer: 10 neutrons

This isotope of fluorine has 9 protons, 9 electrons and 10 neutrons.

Explanation:

Answer:

1)Na20

let the valency of Na is x

2(x)+2=0

+2x+2=0

2x=-2

x=-1

2)ZnO

let the valency of Zn is x

x+2=0

x=-2

3)Al2O3

let the valency of Al is x

2(x)+3(2)=0

2x+6=0

2x=-6

x=-3

4)MgO

let the valency of Mg is x

x+2=0

x=-2

Answer:

Option B. Keq = [CO2] [CaO]/ [CaCO3]

Explanation:

The balanced equation for the reaction is given below:

CaCO3(s) —> CaO(s) + CO2(g)

The expression for the equilibrium constant, Keq is simply the ratio of the concentration of the products to that of the reactants.

The expression for the equilibrium constant, Keq is given below:

Keq = [CO2] [CaO] / [CaCO3]

Answer: c) Keq= [co2]

Explanation:

edge 2023

Answer:

3

Explanation:

Answer:

Radio waves are a type of electromagnetic radiation and they use it for communication for things like phones,computers, and just mobile devices.

An object in motion, will remain at a constant velocity unless an unbalanced force comes upon it and that is a proven fact.

Answer:

80 MOLES OF WATER ARE PRODUCED WHEN 20 MOLES OF PROPANE ARE BURNED IN EXCESS OXYGEN ON A GAS GRILL.

Explanation:

Equation for the reaction:

C3H8 + 5 O2 --------->  4 H2O + 3 CO2 + Heat

The above equation is in the presence of excess oxygen.

In this reaction,

1 mole of propane forms 4 moles of H2O

If 20 moles of propane were to be used, how many moles of water will be produced?

1 mole of propane = 4 moles of water

20 moles of propane = ( 4 * 20 ) moles of water

= 80 moles of water.

So, if 20 moles of propane were burned in excess oxygen, 80 moles of water will be formed. Propane is heavier than air and when properly combusted produces a large amount of heat. It is also non toxic.

80 MOLES OF WATER are produced when 20.0 moles of propane are burned in excess oxygen on a gas grill.

C₃H₈ + 5 O₂ --------->  4 H₂O + 3 CO₂ + Heat

The above equation is in the presence of excess oxygen.

In this reaction, 1 mole of propane forms 4 moles of H₂O

1 mole of propane = 4 moles of water

20 moles of propane = ( 4 * 20 ) moles of water

20 moles of propane= 80 moles of water.

Thus, if 20 moles of propane were burned in excess oxygen, 80 moles of water will be formed.

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