i need help please help me now please

Answer:

Ok what question

Explanation:

Answer:

B. Iron (7.8 g/mL)

Explanation:

23.4/3 = 7.8

7.8g/mL

The identity of a sample of a metal that has a mass of 23.4 g and a volume of 3.0 mL is iron with a density of 7.8g/mL.

The density of a substance can be calculated by dividing the mass of the substance by its volume. That is;

Density = mass (g) ÷ volume (mL)

According to this question, a sample of a metal has a mass of 23.4 g and a volume of 3.0 mL. The density of the metal is as follows:

Density = 23.4g ÷ 3mL

Density = 7.8g/mL

Therefore, the identity of a sample of a metal that has a mass of 23.4 g and a volume of 3.0 mL is iron with a density of 7.8g/mL.

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Answer:

smooth, skeletal, cardiac

contract

actin and myosin

Explanation:

edge

Answer:

The correct answers are

smooth, skeletal, cardiac

contract

actin and myosin

Answer:

2 Nitrogen

Explanation:

This is because it says Diammonium Hydrogen Phosphate. Here. (NH4)3PO4 is one way to write this. However, another way to write this is (NH4)2HPO4. There should be in fact two ammonium groups, NH4 and 1 Hydrogen to get 3+ charge to balance the 3- charge from the Phosphate.

Answer:4

Explanation:

4

Answer:

Lithium would require the least amount of energy to remove an electron

Answer:

The answer is actually sodium

Explanation:

Lithium actually requires more than sodium.

Answer:

I will not consider electronic mass here. We know (the masses should have been provided in the question!) that the neutron mass is

1.008701

⋅

amu

and the proton mass is

1.007316

⋅

amu

.

Explanation:

Question answered

Answer:

Explanation:

molecular weight of potassium hydrogen phthalate = 204

.8094 g of KHP = .8094 / 204 = 3.967 x 10⁻³ moles

3.967 x 10⁻³ moles of KHP must have reacted with 3.967 x 10⁻³ moles of NaOH

concentration of NaOH = 3.967 x 10⁻³ / 40.25 x 10⁻³

= .098 M .

Answer: C

Explanation:

Answer:

Tobacco use: The most preventable cause of cancer death

Explanation:

cancer might not be right

A descriptive model of Earth's layers can be categorized as prototype model. Hence, option B is correct.

What is a descriptive model?

A descriptive model describes a system or other entity and its relationship to its environment.

The Earth has different compositional and mechanical layers. Compositional layers are determined by their components, while mechanical layers are determined by their physical properties.

The outermost solid layer of a rocky planet or natural satellite. Chemically distinct from the underlying mantle.

Hence, option B is correct.

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Answer:

epithelial tissue, connective tissue, muscle tissue, and nerve tissue

Explanation:

Answer:

compound ahhhhhhhhhhhhhgh

Answer: The formula for magnesium carbonate is MgCO_3.

Explanation:

Answer:

C. Elements bond in a multitude of ways to make compounds.

Answer:

The number of its protons and electrons are 82 each

Explanation:

Atomic no of an element = 82

Atomic no = No of protons

⇒ No of protons = 82

Electrons are negatively charged particle and Protons are positively charged particles.

No of electrons = 82

Hence, the element is Lead with 82 protons and electrons

Answer:

A=no

B= yes when liquid or solution

C=yes

D=no

E=yes

Explanation:

According to the given table, the placement of items A-E are

A) ⇒ No

B) ⇒Yes, when liquid or solution

C) ⇒Yes

D) ⇒No

E) ⇒Yes

What is conductivity and Malleability?

Malleability - Those metals that can be beaten into thin sheets with a hammer or any heavy object. For example - Cu, Au etc

Conductivity - Conductivity is the measure of the ease at which an electric charge or heat can pass through a material. For example - Metals are good conductors of heat and electrolytic solution is conductors of electricity.

Therefore, according to the given table, the placement of items A-E are

A) ⇒ No

B) ⇒Yes, when liquid or solution

C) ⇒Yes

D) ⇒No

E) ⇒Yes

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Answer:

The answer is

[tex]3.77 \times {10}^{15} \: \: \: Hz[/tex]

Explanation:

The frequency of the photon can be found by using the formula

[tex]f = \frac{E}{h} \\ [/tex]

where

E is the energy

f is the frequency

h is the Planck's constant which is

6.626 × 10-³⁴ Js

From the question

E = 2.50 × 10^-18 J

So we have

[tex]f = \frac{2.50 \times {10}^{ - 18} }{6.626 \times {10}^{ - 34} } \\ [/tex]

We have the final answer as

[tex]3.77 \times {10}^{15} \: \: \: Hz[/tex]

Hope this helps you

Answer:

Distillation will be the best method for the separation of solute from the solvent in a solution.

Explanation:

Answer:

the atoms are rearranged

Explanation:

they are just in a diff order

The particle diagram represents a chemical change because the breaking of old chemical bonds and the formation of new chemical bonds occurs and a completely new substance is formed.

A chemical change is when a chemical substance is completely transformed into one or more different types of substances. Chemical changes occur through chemical reactions and result in substances with different and new chemical and physical properties.

Chemical changes are irreversible in nature and are also known as permanent changes. When chemical responses occur, the molecules are modified and joined by an energy change as new molecules are produced.

Examples of chemical changes: burning of coal, rusting of iron, digestion of food, adding vinegar to baking soda,  germination of seeds, ripening of fruits, cooking an egg, etc.

The given diagram is quite similar to the water formation reaction:

2H₂   + O₂  [tex]\longrightarrow[/tex] 2H₂ O

In which the bond between the hydrogen atoms and oxygen atoms is broken and the formation of the O-H bond, therefore, is a chemical change.

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Answer:

449 g/L

0.449 g/mL

Explanation:

Step 1: Given data

Step 2: Calculate the density (ρ) of the baseball in g/L

The density is equal to the quotient between the mass and the volume.

ρ = m / V

ρ = 350 g / 0.780 L

ρ =449 g/L

Step 3: Convert ρ from "g/L" to "g/mL"

We will use the conversion factor 1 L = 1000 mL.

449 g/L × (1 L/1000 mL) = 0.449 g/mL

Answer:

Mass percentage of NH₄Cl = 3.54%

Mass percentage of K₂CO₃ = 1.01%

Explanation:

If a 200.0 mL aliquot produced  0.105 g of KB(C₆H₅)₄, then a 100.0 mL aliquot would produce 1/2 * 0.105 g = 0.0525 g of KB(C₆H₅)₄.

Therefore, mass of NH₄B(C₆H₅)₄ in the 100.0 ml aliquot = (0.277 - 0.0525)g = 0.2245 g

Number of moles of NH₄B(C₆H₅)₄ in 0.2245 g = 0.2245 g/ 337.27 g/mol = 0.0006656 moles

In 500 ml solution, number of moles present = 0.0006656 * 500/100 = 0.003328 moles.

From equation of the reaction; mole ratio of  NH₄⁺ and NH₄B(C₆H₅)₄ = 1:1

Similarly, mole ratio of  NH₄⁺ and NH₄Cl = 1:1

Therefore, moles of NH₄Cl in 500 ml sample = 0.003328 moles

Mass of NH₄Cl  = 0.003328 mol * 53.492 g/mol = 0.178 g

Mass percentage of NH₄Cl = (0.178/5.025) * 100% = 3.54%

Number of moles of KB(C₆H₅)₄ in 0.105 g (precipitated from 200.0 ml aliquot) = 0.105 g/ 358.33 g/mol = 0.000293 moles

In 500 ml solution, number of moles present = 0.000293 * 500/200 = 0.0007326 moles.

From equation of the reaction; mole ratio of  K⁺ and KB(C₆H₅)₄ = 1:1

Similarly, mole ratio of  K⁺ and K₂CO₃ = 2:1

Therefore, moles of K₂CO₃ in 500 ml sample = 0.0007326/2 moles =  0.0003663 moles

Mass of  K₂CO₃ = 0.0003663 mol * 138.21 g/mol = 0.05063 g

Mass percentage of K₂CO₃ = (0.05063/5.025) * 100% = 1.01%

Answer: 24.309amu

Explanation:

Answer:

2,3,5

Explanation: