7th grade science , help me please :))

Moles of PF₃ : 4

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.

Reaction

[tex]\tt P_4(s)+6F_2(g)\rightarrow 4PF_3(g)[/tex]

1.25 moles of P₄(s) is reacted with 6 moles of F₂(g)

Limiting reactant : the smallest ratio (mol divide by coefficient)

P₄ : F₂ =

[tex]\tt \dfrac{1.25}{1}\div \dfrac{6}{6}=1.25\div 1\rightarrow F_2~limiting~reactant(smallest~ratio)[/tex]

mol PF₃ based on mol of limiting reactant(F₂), so mol PF₃ :

[tex]\tt \dfrac{4}{6}\times 6~moles=4~moles[/tex]

Answer:

I think it is true you should go for true

Answer:

C

Explanation:

In the bone marrow, red blood cells are produced

Explanation:

The highest number is the strongest base. Therefore the pH of 12 is the strongest base here (C).

Answer:

C help stop bleeding

Explanation:

Platelets stop bleeding by clumping and forming plugs in blood vessel injuries

Answer:

0.53 mol NaCl

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

3.2 × 10²³ atoms NaCl

Step 2: Identify Conversions

Avogadro's number

Step 3: Convert

[tex]3.2 \cdot 10^{23} \ atoms \ NaCl(\frac{1 \ mol \ NaCl}{6.022 \cdot 10^{23} \ atoms \ NaCl} )[/tex] = 0.531385 mol NaCl

Step 4: Check

We are given 2 sig figs. Follow sig fig rules and round.

0.531385 mol NaCl ≈ 0.53 mol NaCl

Answer:

nuclear force

Explanation:

Explanation:

it's answer is last

hope it helps you

↓ 500 N  represents the net force as the force is acting in downward direction.

Force is defined as a cause which is capable of changing the motion of an object. It can cause an object which has mass to change it's velocity. It is also simply a push or a pull . It has both magnitude as well as direction.Hence, it is a vector quantity.

It has SI units of Newton and is represented by'F'.Newton's second law states that force which acts on an object is equal to momentum which changes with time. If mass of object is constant, acceleration is directly proportional to net force acting on an object.

The concepts which related to force are thrust and torque .Thrust increases the velocity of an object and torque produces change in rotational speed of an object.

Learn more about force,here:

https://brainly.com/question/30507236

#SPJ7

Answer:

highly unstable

Explanation:

also, due to repulsion of lone pairs and instability it breaks and can't form PI5

hope that helps....

Answer:

See explanation

Explanation:

When introduced to hot water, sodium and potassium metals react violently to form a colourless solution and hydrogen gas. The metal becomes spontaneously ignited and burns with its characteristic flame colour.

Magnesium burns with a bright white flame to yield solid magnesium oxide

and hydrogen gas when steam is passed over heated magnesium.

The last question is not clear but I believe that it has to do with reaction of sodium and iron with water. Sodium reacts violently with cold water at room temperature to evolve hydrogen gas and aqueous sodium hydroxide.

Iron reacts with steam at red heat to yield hydrogen gas and Fe3O4

Answer:

c

Explanation:

A 0.85% saline solution would consist of 0.85 g NaCl made up to 100 mL of water.

A 0.85% saline solution contains 0.85% by weight of NaCl. Hence, in order to prepare such a solution, 0.85 g of NaCl is weighed out into a beaker or cylinder and distilled water is added up to the 100 mL mark. On the other hand, 8.5 g of the NaCl can be weighed out and then distilled water added to 1000 mL mark.

The correct option is, therefore, c.

Answer:2518.5J/kg/K

Explanation:

Answer:

Metre

Explanation:

the SI unit of length is Metre

Answer:

The SI unit for length is Meter

Answer:B

Explanation:Because when the object heats up the particles move faster and it will turn into a liquid or gas but if it is being cooled then the particles will slow down and either make a liquid or solid.

Answer:

STP conditions imply a temperature of 273.15 K and a pressure of 100 kPa. When tose conditions are met, 1 mole of any ideal gas will have a volume of 22.7 L. So, if 1 mole occupies a volume of 22.7 L, 2 moles will occupy a volume twice as big. Likewise, 0.5 moles will occupy half the volume 1 mole occupies. Assuming that the gas is at standard temperature and pressure (STP), one mole of any gas occupies 22.4 L . This means the number of moles of O2 is 222.4=0.089 mol .

Explanation:

Answer:

The correct answer is 5,170 J

Explanation:

The heat absorbed by the reaction (Qr) is equal to the heat released by the calorimeter (Qcal):

Qr = - Qcal

We calculate Qcal from the mass of the calorimeter (m), the specific heat (Cp), and the change in temperature (ΔT), as follows::

Qcal = m x Cp x ΔT

We have the following data:

m = 1.400 kg x 1000 g/1 kg = 1,400 g

Cp = 3.52 J/g°C

Initial T = 28.50°C + 273 = 301.50 K

Final T = 27.45°C + 273 = 300.45 K

ΔT = Final T - Initial T = 300.45 K - 301.50 K = -1.05 K

So, we introduce the data in the mathematical expression for Qcal:

Qcal = m x Cp x ΔT = 1,400 g x 3.52 J/g°C x (-1.05 K) = -5,174.4 J ≅ -5,170 J

Therefore, the heat absorbed by the reaction is:

Qr = - Qcal = -(-5,170 J) = 5,170 J

Answer:

D

Explanation:

Just took the test.

Answer:

I⁻

Explanation:

The identity of the element is obtained when the proton number is known.

Mass Number = 127

Neutrons = 74

Number of protons is obtained from;

Protons = Mass Number - Number of Neutrons

Protons = 127 - 74 = 53

The element is Iodine and it's symbol is I.

However, The anion derived from the isotope has 54 electrons

A neutral Iodine should have 53 electrons. This means it has gained a single electron. The symbol is now written as;

I⁻

Answer: Atoms are not able to exist independently

Explanation:

Answer:

when you use energy , the total amount of energy decreases.

Answer: Photosynthesis

Explanation:

Answer:

a) 0.13 bar

b) 5.05 L

Explanation:

Let us take the mass of the mixture to be 100 g. Hence, 70% by weight of dioxygen corresponds to 70 g

Mass of dihydrogen = 100g - 70 g = 30g

Number of moles of dioxygen = 70g/32 g/mol = 2.2 moles of dioxygen

Number of moles of dihydrogen = 30g/2g/mol = 15 moles of dihydrogen

Total number of moles = 2.2 + 15 = 17.2 moles

Mole fraction of dioxygen = 2.2/17.2 = 0.13

Partial pressure = mole fraction * total pressure

Partial pressure of dioxygen = 0.13 * 1 = 0.13 bar

ii) number of moles in 8.8 g of CO2 = 8.8g/44g/mol = 0.2 moles

T = 31.1 + 273 = 304.1 K

P = 1 bar

V= ?

R = 0.083 bar L K-1 mol-1

From

PV=nRT

V = nRT/P

V= 0.2 * 0.083 * 304.1/1

V= 5.05 L

Answer:

Your answer is correct.

Explanation:

The steel paper clip would only move because it has steel in it, which is a magnetized material, plastic on the other side, is made up of polymers which are not attracted to the magnetic force, causing it not to move.

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\[/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

[tex]n = \frac{1.68 \times {10}^{24} }{6.02 \times {10}^{23} } \\ = 2.790697 ...[/tex]

We have the final answer as

Hope this helps you

Answer:

This question is incomplete and lacks options, the complete part and the options are:

Which of the following variables should Sarah change from one group of chamomile to the next?

A. the location of the plants

B. the height of the plants

C. the type of plants

D. the amount of water she gives the plants

The answer is A

Explanation:

This question is asking for the INDEPENDENT VARIABLE in the experiment. The independent variable of an experiment is the variable that is changed or manipulated by the experimenter in order to bring about a response.

In this experiment where Sarah wants to know where in her garden chamomile plants would grow the best. She hypothesizes that chamomile will grow best in the corner of the garden that gets the most sunlight. However, to test this hypothesis, she decides to plant several groups of chamomile in her garden as an experiment. The variable that Sarah can change in the several groups of chamomile (independent variable) is the LOCATION OF THE PLANTS.

Note that, "where" is a question of location.

Answer:

The answer is C

Explanation:

Answer:

The one thing they have in common is that They are mixtures

Answer:

they are both mixtures

Explanation:

Answer:

See explanation

Explanation:

According to Newton's second law, the rate of change of momentum is proportional to the impressed force.

Mathematically;

Ft = mv - mu

Where;

F = Force

t = time

m= mass

v = final velocity

u = initial velocity

Since the mass is the same, the equation reduces to;

Ft = m(v-u)

So

F=  m(v-u)/t

but

(v-u)/t = acceleration (a)

F = ma

a = F/m

Since the mass is the same because Sarah is the same size as i am but she pulls with a greater force, it follows that i will be the one in the wagon when the wagon has the greatest acceleration because the force that Sarah applies when pulling me is greater than the force i will apply when pulling her.

Answer:

prolly chickens