pls i need help with this

Pls I Need Help With This

Answers

Answer 1

Answer:

C

Explanation:

A physical change is one in which no new substance is formed. The moistening of food by saliva is purely a physical change because no new substance is formed in the process.

A chemical change leads to the formation of a new substance. The action of the enzyme converts starch into sugar which means that a new substance is formed. This is a chemical change.


Related Questions

What is the volume of an object if the density is 8g/cm^3 and has a mass of 16g? *
1 point
8mL
128mL
16mL
2mL

Answers

Answer:

I think the answer is 2mL.

Explanation:

i hope it help.

how do i balance the first chemical reaction above?? plz plz help

Answers

Answer:

2K +F₂→ 2KF

Explanation:

When we balance an equation, we are trying to ensure that the number of atoms of each element is the same on both sides of the arrow.

On the left side of the arrow, there is 1 K atom and 2 F atoms. On the right, there is 1 K and 1 F atom.

Since the number of K atoms is currently balanced, balance the number of F atoms.

K +F₂→ 2KF

Now, that the number of F atoms is balanced on both sides, check if the number of K atoms are balanced.

Left

K atoms: 1

F atoms: 2

Right

K atoms: 2

F atoms: 2

The number of K atoms is not balanced.

2K +F₂→ 2KF

Left

K atoms: 2

F atoms: 2

Right

K atoms: 2

F atoms: 2

The equation is now balanced.

half equation for oxygen to oxide ions, aluminium ions to aluminium, magnesium to magnesium ions

Answers

2mg(s)+02(g)=2mg0 that was the correct answer

The molar solubility of calcium sulfide in a 0.222 M sodium sulfide solution is:________-

Answers

Sorry I don’t get the question Buh I’m sure you’ll get it eventually

For the following reaction conditions select the correct statement regarding the reaction below.
OH Cl OTs OTs N TsCl W X Y Z N
a. W is the correct product.
b. X is the correct product.
c. Y is the correct product.
d. Z is the correct product since pyridine acts as a nucleophile.
e. Both X and Y are both formed in this reaction as a racemic mixture

Answers

Answer:

B

Explanation:

The appropriate diagram of the question is shown in the first image attached below.

From the diagram, we see the reaction of Cyclopentanol taking place under Tscl pyridine. We are to show the reaction mechanism and determine from the options, which appropriate product fits in.

So, from the reaction, the hydroxyl substituent reacts with Tscl where cl is being lost. This process is followed by an attack of N substituent on the pyridine with the Hydrogen atom and cleaves off for the structure to form a stable structure. The stereochemistry of the compound remains unchanged and it maintains its stick formula.

Thus, X is the appropriate and the correct product.

Global climate change is

a.
a politically motivated deception generated by scientists with an environmentalist agenda.

b.
hotly debated by a deeply divided scientific community.

c.
a hypothesis that is not yet well supported by scientific evidence.

d.
understood by science to be a fact, and as largely the result of human activities.

Answers

It’s d man..........

please need help..
no attachments thankyou

1. A sample of a chemical compound has 2.96g carbon, 0.414g hydrogen, 0.675g oxygen and 2.96 sulphur.
calculate it's empirical formula.

2.if it's mass was 972g, determine its molecular formula.​

Answers

Answer:

1. The empirical formula => C₆H₁₀OS₂

2. Molecular formula => C₃₆H₆₀O₆S₁₂

Explanation:

1. Determination of the empirical formula.

Carbon (C) = 2.96 g

Hydrogen (H) = 0.414 g

Oxygen (O) = 0.675 g

Sulphur (S) = 2.96 g

Divide by their molar mass

C = 2.96 / 12 = 0.247

H = 0.414 / 1 = 0.414

O = 0.675 / 16 = 0.042

S = 2.96 / 32 = 0.0925

Divide by the smallest

C = 0.247 / 0.042 = 6

H = 0.414 / 0.042 = 10

O = 0.042 / 0.042 = 1

S = 0.0925 /0.042 = 2

Therefore, the empirical formula is

C₆H₁₀OS₂

2. Determination of the molecular formula.

Molar mass of compound = 972 g/mol

Empirical formula => C₆H₁₀OS₂

Molecular formula =>?

Molecular formula = [C₆H₁₀OS₂]ₙ

Molecular formula = molar mass of compound

Thus,

[C₆H₁₀OS₂]ₙ = 972

[(12×6) + (10×1) + 16 + (32×2)]n = 972

[72 + 10 + 16 + 64]n = 32

162n = 972

Divide both side by 162

n = 972 / 162

n = 6

Molecular formula = [C₆H₁₀OS₂]ₙ

Molecular formula = [C₆H₁₀OS₂]₆

Molecular formula = C₃₆H₆₀O₆S₁₂

A container is filled with helium gas. It has a volume of 2.25 liters and contains 9.00 moles of helium. How many moles of helium could be held in a 1.85 liter container at the same temperature and pressure?

Answers

Answer: There are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.

Explanation:

Given: [tex]V_{1}[/tex] = 2.25 L,     [tex]n_{1}[/tex] = 9.0 mol

[tex]V_{2}[/tex] = 1.85 L,            [tex]n_{2}[/tex] = ?

Formula used to calculate the moles of helium are as follows.

[tex]\frac{V_{1}}{n_{1}} = \frac{V_{2}}{n_{2}}\\[/tex]

Substitute the values into above formula as follows.

[tex]\frac{V_{1}}{n_{1}} = \frac{V_{2}}{n_{2}}\\\frac{2.25 L}{9.0 mol} = \frac{1.85 L}{n_{2}}\\n_{2} = \frac{1.85 L \times 9.0 mol}{2.25 L}\\= 7.4 mol[/tex]

Thus, we can conclude that there are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.

explain how dna which is 6 feet long, can be stored in the nucleus of a tiny human cell.

Answers

Answer:

Packed inside the nucleus of every human cell are nearly 6 feet of DNA, which is divided into 46 individual molecules, one for each chromosome and each about 1.5 inches long. Packing all this material into a microscopic cell nucleus is an extraordinary feat of packaging.

Explanation:

Packed inside the nucleus of every human cell are nearly 6 feet of DNA, which is divided into 46 individual molecules, one for each chromosome and each about 1.5 inches long. Packing all this material into a microscopic cell nucleus is an extraordinary feat of packaging. For DNA to function, it can't be crammed into the nucleus like a ball of string. Instead, it is combined with proteins and organized into a precise, compact structure, a dense string-like fiber called chromatin.

(hope this helps can i plz have brainlist :D hehe)

[H3O+] = 3.6 x 10-2 M

Answers

Answer:

Explanation:

Hello there!

In this case, since this concentration of hydronium ions is given, we infer we may calculate that of the hydroxide ions, pH and pOH because no question was specifically given. That is why we proceed as follows:

-  pH: Here, we use this concentration to calculate the pH according to the negative logarithm:

[tex]pH=-log(3.6x10^{-2})=1.44[/tex]

Which means that the solution is acidic as the pH is less than 7.

- pOH: since the pH added to the pOH is 14, we can calculate the latter as follows:

[tex]pOH=14-1.44=12.56[/tex]

- Hydroxide concentration: Given the pOH, we apply the antilogarithm to calculate such concentration as shown below:

[tex][OH^-]=10^{-pOH}=10^{12.56}=2.75x10^{-13}M[/tex]

Keep in mind, this is an arbitrary solution because no question was provided.

Regards!

SOMEONE HELP ME
1. How many grams of C are present in 4.86 grams of carbon dioxide
?
grams C.
2. How many grams of carbon dioxide contain 1.73 grams of O ?
grams carbon dioxide.

Answers

Answer:

1. 1.33 gram of carbon

2. 2.38g of carbon dioxide

Explanation:

From the given information:

Total amount of CO₂ = 4.86 grams

Atomic mass of C = 12 g/mole

molar mass of CO₂ = 44 g/mole

The mass of the Carbon (C) in grams is:

[tex]= Total\ amount \ of \ CO_2 \times \dfrac{12 \ g/mol}{44 \ g/mol}[/tex]

[tex]= 4.86 \ g \times \dfrac{12 \ g/mol}{44 \ g/mol}[/tex]

= 1.33 gram of carbon

2.

Here, the total amount of CO₂ = unknown

Atomic mass of O₂ = 32 g/mole

molar mass of CO₂ = 44 g/mole

amount of oxygen = 1.73 g

The mass of CO₂ = [tex]Total \ amount \ of \ O_2 \times \dfrac{44 \ g/mol}{32\ g/mol}[/tex]

[tex]=1.73 \times \dfrac{44 \ g/mol}{32\ g/mol}[/tex]

= 2.38 g of carbon dioxide

Small amount of acid is added to Water during electrolysis of water . Why?​

Answers

Answer:

Water doesn't have ions that are needed to pass the electricity so in order to increase the no of ions we poor acid into the water. Just increasing the no ions will increase the electricity flow faster

Help!!!

1.
Q: How does the distillation apparatus remove impurities from water?

Q: Why does water vapour condense in the condenser tube?

Q: As the boiling animation neared the end, what does the change in the proportion of particle types in the boiling flask indicate about the impurities?

Answers

Answer:

Q1) Distillation relies on evaporation to purify water

Explanation:

contaminated water is heated to form steam. inorganic compounds and large non-volatile organic molecules do not evaporate with the water and are left behind. The steam then cools and condenses to form purified water

PLSSS HELP ME THIS IS FOR SIENCE PLLLLSSSSS
The passing of heat through a material is called ________.
A. vibration
B. conduction
C. radiation
D. convection

Answers

Answer:

Conduction

Explanation:

I took the course

Answer:

B. conduction

Which explanation describes the first part of a chemical reaction? Reactants collide to form products. Products collide to form reactants. Products collide to form a transition state. Reactants collide to form a transition state.

Answers

Answer:

Reactants collide to form a transition state.

Explanation:

So sorry if I’m wrong but I feel this is right

To solve such this we must know the concept of chemical reaction. The correct option is option B that is atoms in one compound switch places with atoms in another compound.

What is chemical reaction?

Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved.

There are so many types of chemical reaction reaction like combination reaction, double displacement reaction, combustion reaction, displacement reaction. "Reactants collide to form a transition state" describes the first part of a chemical reaction.

Therefore "Reactants collide to form a transition state" describes the first part of a chemical reaction. The correct option is option B.

Learn more about the chemical reactions, here:

https://brainly.com/question/3461108

#SPJ2

A molecule or ion that donates the hydrogen in a hydrogen bond is a hydrogen bond donor.

a. True
b. False

Answers

Answer: The statement 'a molecule or ion that donates the hydrogen in a hydrogen bond is a hydrogen bond donor' is true.

Explanation:

A molecule or ion that donates hydrogen in a hydrogen bond is called a hydrogen donor.

For example, [tex]NH_{3} + H_{2}O \rightarrow NH^{+}_{4} + OH^{-}[/tex]

Here, [tex]NH_{3}[/tex] is donating the hydrogen ion to water molecule. Whereas water is accepting the hydrogen ion so water is a hydrogen bond acceptor. Therefore, hydrogen bond is formed by [tex]NH_{3}[/tex].

Thus, we can conclude that the statement 'a molecule or ion that donates the hydrogen in a hydrogen bond is a hydrogen bond donor' is true.

4. A student poured 50 cm^3
water into a beaker and
measured the water's
temperature. The student added
1.00 g calcium chloride to the
water, stirred the mixture and
then recorded the temperature.
The concentration of a calcium
chloride solution is 12 g/dm^3.
Calculate the volume of this
solution, in cm^3, that contains
9.0 g of calcium chloride.

Answers

Answer:

V = 750 cm³

Explanation:

The volume of the solution can be calculated by the following formula:

[tex]V = \frac{M}{C}[/tex]

where,

V = Volume of solution = ?

M = Mass of Calcium Chloride = 9 g

C = Concentration of Solution = 12 g/dm³

Therefore,

[tex]V = \frac{9\ g}{12\ g/dm^3}\\\\V = (0.75 dm^3)(\frac{1000\ cm^3}{1\ dm^3})[/tex]

V = 750 cm³

Consider this reaction at equilibrium:

2BrNO (g) → 2NO (g)+ Br2 (g)

Predict whether the reaction will shift left, shift right, or remain unchanged after each disturbance.

a. NO is added to the reaction mixture
b. BrNO is added to the reaction mixture
c. Br2 is removed from the reaction mixture
d. Pressure is increased

Answers

Answer:

a. NO is added to the reaction mixture ⇒ to the left

b. BrNO is added to the reaction mixture ⇒ to the right

c. Br₂ is removed from the reaction mixture ⇒ to the right

d. Pressure is increased ⇒ to the left

Explanation:

The reaction at equilibrium is the following:

2BrNO (g) → 2NO (g)+ Br₂ (g)

The left side is the reactants side (2 BrNO) and the right side is the products side (2 NO + Br₂).

a. NO is added to the reaction mixture

NO is a product, in the right side of the equation. If a product is added, the equilibrium will shift to the opposite side, to the left, to form more reactants and compensate for the addition.

b. BrNO is added to the reaction mixture

BrNO is a reactant, in the left side of the equation. If a reactant is added to a reaction at equilibrium, more product will be formed in compensation. Therefore, the equilibrium will shift to the right.

c. Br₂ is removed from the reaction mixture

Br₂ is a product, in the right side. If it is removed, the system will compensate for the remotion by forming more product, so the reaction will shift to the right.

d. Pressure is increased

Since both reactants and products are in the gas phase, the equilibrium is affected by pressure. If pressure is increased, the equilibrium will shift to the side of the reaction with the fewest number of moles. The reactants side (left) has 2 moles of BrNO while the products side (right) has 3 moles (1 mol NO + 1 mol Br₂ = 3 moles of gas). Therefore, the reactants side has the fewest number of moles, so the equilibrium will shift to the left.

How many grams of NaOH are contained in 5.0*10ml of a0. 77 sodium hydroxide solution

Answers

Answer:

1.54grams

Explanation:

Molarity of a solution = n/V

Where;

n = number of moles (mol)

V = volume (L)

Based on the information given in this question;

Volume of NaOH solution = 5.0 × 10ml

= 50ml = 50/1000 = 0.050 L

Molarity = 0. 77 M

Using; Molarity = n/V

0.77 = n/0.05

n = 0.77 × 0.05

n = 0.0385mol

To find the mass (grams) of NaOH in the solution, we use the following formula:

mole (n) = mass/molar mass

Molar mass of NaOH = 23 + 1 + 16 = 40g/mol

0.0385 = mass/40

mass = 0.0385 × 40

mass = 1.54grams.

How many moles are in 20.5 grams of Calcium (Ca)? (1pt)
A)762.45 moles
B)1 mole
C)2 moles
D)0.5 moles

Answers

Answer:

Number of moles in 20.5 grams of calcium (Ca) = 0.5 moles (Approx.)

Explanation:

Given:

Amount of calcium (Ca) = 20.5 grams

Find:

Number of moles in 20.5 grams of calcium (Ca)

Computation:

Number of moles = Gram weight / Atomic weight of substance

We know that, Atomic weight of calcium (Ca) is 40.078 u

Number of moles in 20.5 grams of calcium (Ca) = Amount of calcium (Ca) / Atomic weight of calcium (Ca)

Number of moles in 20.5 grams of calcium (Ca) = 20.5 / 40.078

Number of moles in 20.5 grams of calcium (Ca) = 0.511

Number of moles in 20.5 grams of calcium (Ca) = 0.5 moles (Approx.)

The oceanic crust is destroyed at convergent boundaries because it_______________________ *
a) diverges to form a rift valley
b) goes into a subduction zone where it is melted by the hot magma
c) transforms
d) the rock crumbles at an ocean ridges

Answers

Answer: I believe the answer is d)  the rock crumbles at an ocean ridges

Explanation:

8. Calculate (H^+), (OH^-), pOH and the pH for a 0.00024 M solution of calcium hydroxide. Must show work!

Answers

Answer:

1. [H⁺] = 2.0×10¯¹¹ M

2. [OH¯] = 4.8×10¯⁴ M

3. pOH = 3.3

4. pH = 10.7

Explanation:

From the question given above, the following data were obtained obtained:

Molarity of Ca(OH)₂ = 0.00024 M

We'll begin by calculating the concentration of the hydroxide ion [OH¯]. This can be obtained as follow:

Ca(OH)₂ (aq) —> Ca²⁺ + 2OH¯

From the balanced equation above,

1 mole of Ca(OH)₂ produced 2 moles of OH¯.

Therefore, 0.00024 M Ca(OH)₂ will produce = 2 × 0.00024 = 4.8×10¯⁴ M OH¯

Thus, the concentration of the hydroxide ion [OH¯] is 4.8×10¯⁴ M

Next, we shall determine the pOH of the solution. This can be obtained as follow:

Concentration of the hydroxide ion [OH¯] = 4.8×10¯⁴ M

pOH =?

pOH = –Log [OH¯]

pOH = –Log 4.8×10¯⁴

pOH = 3.3

Next, we shall determine the pH of the solution. This can be obtained as follow:

pOH = 3.3

pH =?

pH + pOH = 14

pH + 3.3 = 14

Collect like terms

pH = 14 – 3.3

pH = 10.7

Finally, we shall determine the concentration of hydrogen ion [H⁺]. This can be obtained as follow:

pH = 10.7

Concentration of hydrogen ion [H⁺] =?

pH = –Log [H⁺]

10.7 = –Log [H⁺]

Divide both side by –1

–10.7 = Log [H⁺]

Take the antilog of –10.7

[H⁺] = Antilog (–10.7)

[H⁺] = 2.0×10¯¹¹ M

SUMMARY:

1. [H⁺] = 2.0×10¯¹¹ M

2. [OH¯] = 4.8×10¯⁴ M

3. pOH = 3.3

4. pH = 10.7

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