pless answer thisss!!​

Answer:

4.8 x 10^1

Explanation:

Move the decimal so there is one non-zero digit to the left of the decimal point. The number of decimal places you move will be the exponent on the 10. If the decimal is being moved t the right, exponent will be negative. If the decimal is being moved to the left, the exponent will be positive.

Answer:

See explanation

Explanation:

DDT is dichlorodipphenylrtrichloroethane. It is was a popular insecticide used for agricultural purposes. Racheal Carson's book, silent springs drew attention to the use of insecticides such as DDT in agriculture.

DDT is a non-biodegradable, fat-soluble compound. It enters into the food chain and has the ability to bioaccumulate in the human body where it becomes deposited in the adipose tissue.

There is no direct harmful effect of DDT to humans, however, when oxidation of DDT takes place in body many harmful metabolites  are released into the body causing harmful effects to human health such as; breast cancer, male infertility, miscarriages and low birth weight, developmental delay and liver damage.

There is convincing empirical evidence supporting the carcinogenicity of DDT its main metabolites DDE and DDD, however, many studies on the harm caused by DDT and its main metabolites in the body have so far led to inconclusive, and sometimes negative, results

Answer: Yes.

Explanation:

the number of protons in the nucleus determines an element's identity. Chemical changes do not affect the nucleus, so chemical changes cannot change one type of atom into another. The number of protons in a nucleus does change sometimes, however. The identity of the atom, therefore, changes.

Answer:

C

Explanation:

the rest arent scientific

Answer:

C. Investigations

Explanation:

Test approved

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Answer:

T₂ =  344.8 K

Explanation:

Given data:

Initial volume of gas = 475 cm³

Initial temperature = 273 K

Final volume = 600 cm³

Final temperature = ?

Solution:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume  

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

T₂ = T₁V₂/V₁  

T₂ = 273 K × 600 cm³ /  475 cm³

T₂ = 163800K . cm³ / 475 cm³

T₂ =  344.8 K

Answer:

The block is made up of aluminum.

density = 2.7 g/cm³

Explanation:

Given data:

Dimension of metal block = 2.0 cm×2.5 cm× 3.0 cm

Mass of block = 40.05 g

Density of block = ?

Which metal is this = ?

Solution:

Density:

Density is equal to the mass of substance divided by its volume.

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Volume of block = 2.0 cm×2.5 cm× 3.0 cm = 15 cm³

d = m/v

d = 40.5 g/ 15 cm³

d = 2.7 g/cm³

The block is made up of aluminum.

Answer:

1.1 x [tex]10^{9}[/tex] km/h

Explanation:

Here we need to do two conversions- one from centimetres to kilometres and one from seconds to hours.

To get from cm to km- we divide by 100 000 since there are 100 000 cm in a km.

To get from seconds to hours we divide by 3600 since there are 3600 seconds in an hour

[tex]\frac{3*10^{10}cm/100000 }{1second/3600} =1.1*10^{9} km/h[/tex]

Answer:

V = 34.55 L

Explanation:

Given that,

No of moles, n = 1.4

Temperature, T = 20°C = 20 + 273 = 293 K

Pressure, P = 0.974 atm

We need to find the volume of the gas. It can be calculated using Ideal gas equation which is :

PV=nRT

R is gas constant, [tex]R=0.08206\ L-atm/mol-K[/tex]

Finding for V,

[tex]V=\dfrac{nRT}{P}\\\\V=\dfrac{1.4\times 0.08206\times 293}{0.974 }\\\\V=34.55\ L[/tex]

So, the volume of the gas is 34.55 L.

The density of the wood : 1.45 g/cm³

Density is a quantity derived from the mass and volume  

Density is the ratio of mass per unit volume  

With the same mass, the volume of objects that have a high density will be smaller than objects with a smaller type of density  

The unit of density can be expressed in g/cm³ or kg/m³  

Density formula:  

[tex]\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}[/tex]

ρ = density  

m = mass  

v = volume  

[tex]\tt V=2.7\times 5.5\times 3.9=57.915~cm^3[/tex]

[tex]\tt \rho=\dfrac{m}{V}\\\\\rho=\dfrac{84~g}{57.915~cm^3}=\boxed{\bold{1.45`g/cm^3}}[/tex]

Answer: false 100

Explanation:

if this is the true or false test here

Answer:

B

Explanation:

Just did it on usa test prep

The element which is most likely to be magnesium  is the element with the electronic configuration same as magnesium.

It is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.

Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.

The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.

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✅Paraphrasing and summarizing .✅

IamSugarBee

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

So we have

[tex]density = \frac{25}{90} = \frac{5}{18} \\ = 0.277777...[/tex]

We have the final answer as

Hope this helps you

Answer:

O microwaves, radio waves, infrared light

Explanation:

Answer: C.  microwaves, radio waves, infrared light

Explanation: C. Microwaves, Radio Waves, Infrared light

Answer:

.

Answer: 5 All of the molecules have the same kinetic energy

since the temperature is kept constant at 298 K

Explanation:

The AVERAGE kinetic energy is directly proportional to the absolute temperature.

All the molecules have the same average kinetic energy as average kinetic energy is directly proportional to the absolute temperature. So, the correct option is 5.

The average kinetic energy (K) is equal to one-half of the mass (m) of each gas molecule times the root mean square speed (Vrms) squared.

We know that the average kinetic energy is directly proportional to the absolute temperature.

All of the molecules have the same kinetic energy since the temperature is kept constant at 298 K.

Therefore, All the molecules have the same average kinetic energy as average kinetic energy is directly proportional to the absolute temperature.

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Answer:

Explanation:

The overall equation for this reaction can be represented as:[tex]4 Fe(s) + 3 O_{2(g) } \to 2Fe_2O_{3(s)} \ \ \ \ \Delta H = -1652 \ kJ[/tex]

The first question says:

How much heat is released when 4.40 moles of iron is reacted with excess O₂?

Suppose 1652 kJ of heat is being emitted into the surroundings when four(4) moles of Fe reacted with O₂, therefore;

4.40 moles of Fe reacts with:

[tex]=\dfrac{4.40 \ moles \times 1652 \ kJ}{4 \ moles}[/tex]

= 1817.2 kJ of heat will be produced.

The second question says:

How much heat is released when 1.00 mole of [tex]Fe_2O_3[/tex] is produced?

Given that 1652 kJ of heat is being emitted into the surroundings when two(2) moles of [tex]Fe_2O_3[/tex] is produced, therefore;

1.00 moles of [tex]Fe_2O_3[/tex] reacts with:

[tex]=\dfrac{1.00 \ moles \times 1652 \ kJ}{2 \ moles}[/tex]

= 826 kJ of heat will be produced.

To the third question; we have:

How much heat is released when 1.60 g iron is reacted with excess O₂?

We need to find the number of moles of iron first.

We know that number of moles = mass/molar mass

Thus, the molar mass of iron = 55.8 g/mol

number of moles of iron = (1.60g) / (55.8 g/mol)

number of moles of iron = 0.02867 mol

Thus; [tex]\dfrac{0.02867\ mol \times 1652 \ kJ }{4 \ mol}[/tex]

= 11.84 kJ of heat is released.

The last question says:

How much heat is released when 11.8 g Fe and 1.20 g O₂ are reacted?

Again;

the number of moles of Fe = (11.8g) / (55.8 g/mol) = 0.2114 mole of Fe

Thus; [tex]\dfrac{0.2114\ mol \times 1652 \ kJ }{4 \ mol}[/tex]

= 87.31 kJ of heat is released.

On the other hand,

the number of moles of O₂ = (1.20g) / (32 g/mol) = 0.0375 mol of O₂

Thus; [tex]\dfrac{0.0375\ mol \times 1652 \ kJ }{3 \ mol}[/tex]

= 20.65 kJ of heat is released

Therefore, when these two(2) reactants reacted with each other, it is just the smaller amount of heat that would be released because oxygen tends to be the limiting reactant.

Answer:

Proust's law of definite proportion

Explanation:

The law of constant proportion states that the components elements of a given chemical compound combine with each other in a fixed mass ratio when the compound is produced by any given process

Therefore, from the question, the chemical formula for Nitrogen Dioxide is NO₂, where the molar mass of nitrogen, N = 14

The molar mass of oxygen, O = 16

Given that one molecule of NO₂, contains one atom of nitrogen and two atoms of oxygen, one mole of NO₂ will contain 14 grams of nitrogen and 32 grams of oxygen, according to Proust's law of definite proportion.

Alkanes are saturated hydrocarbons that have single bonds in chains

General formula for alkanes :

[tex]\tt \large{\bold{C_nH_{2n+2}}[/tex]

Hydrocarbon combustion reactions (specifically alkanes)

[tex]\large {\box {\bold{C_nH _ (_2_n _ + _ 2_) + \dfrac {3n + 1} {2} O_2 \Rightarrow nCO_2 + (n + 1) H_2O}}}[/tex]

So that the burning of ethane with air (oxygen):

[tex]\tt C_2H_6+\dfrac{7}{2}O_2\rightarrow 2CO_2+3H_2O[/tex]

2C₂H₆ (g) + 7O₂ (g) ⟶ 4CO₂ (g) + 6H₂O (ℓ)

or we can use mathematical equations to solve equilibrium chemical equations by giving the coefficients for each compound involved in the reaction

C₂H₆ (g) + aO₂ (g) ⟶ bCO₂ (g) + cH₂O (ℓ)

C : left 2, right b ⇒ b=2

H: left 6, right 2c⇒ 2c=6⇒ c= 3

O : left 2a, right 2b+c⇒ 2a=2b+c⇒2a=2.2+3⇒2a=7⇒a=7/2

Answer:

The answer is option D 3

Explanation:

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Answer:

d.3

Explanation:

The Scientific Notation of  Xenon’s density : 1.31293 × 10²

Scientific Notation consists of 2 parts

1. the first part: the first digit followed by the decimal point

2. The second part: the power of 10 which shows the number of digits after the decimal point

Xenon's density = 131.293

First digit = 1, then we give the decimal point and the next digit

The power of 10 is determined from the number of decimal points moved from the original decimal point

Because we move the decimal point two digits to the left, the power of 10 has the number 2 (10²)

So that the Scientific Notation form becomes:

1.31293 × 10²

Answer:

Salt

Explanation:

It has all -

Answer:

Love it because Love it

Explanation:

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question

mass = 30.5 g

volume = 2.2 cm³

We have

[tex]density = \frac{30.5}{2.2} \\ = 13.863...[/tex]

We have the final answer as

Hope this helps you

Answer:

D. Limitations due to ethical concerns about experimental subjects.

Explanation:

Answer:

A

Explanation:

(its my friend)

Answer: C. Saturation point

Explanation:

Answer:

See explanation

Explanation:

The question is incomplete because the image of the alcohol is missing. However, I will try give you a general picture of the reaction known as hydroboration of alkenes.

This reaction occurs in two steps. In the first step, -BH2 and H add to the same face of the double bond (syn addition).

In the second step, alkaline hydrogen peroxide is added and the alcohol is formed.

Note that the BH2 and H adds to the two atoms of the double bond. The final product of the reaction appears as if water was added to the original alkene following an anti-Markovnikov mechanism.

Steric hindrance is known to play a major role in this reaction as good yield of the anti-Markovnikov like product is obtained with alkenes having one of the carbon atoms of the double bond significantly hindered.

Answer:

Photic Zone

Explanation:

The photic zone is the uppermost layer of the sea that recieves sunlight allowing phytoplankton to perform photosynthesis.