Help me plzz and thank u

Answer:

Explanation:

Solution required is .15 M 500 mL sodium fluoride .

molecular weight of sodium fluoride = 42

one mole of sodium fluoride = 42 grams

No of moles contained in the solution of .15M , 500 mL solution

= .15 x 0.5 moles = .075 moles

1 mole = 42 g

.075 moles = .075 x 42 = 3.15 grams .

So mass of sodium fluoride required = 3.15 g .

Answer:

True......................had to do this because we need atleast 20 letters

Answer:1. Introduction

The main air pollutants are represented by gases forms, particles in suspension, different ionizing radiation and noise.

The gases forms are: oxidized and reduced forms of carbon (CO2, CO, CH4), of nitrogen (NO2, NO, N2O4, NH3, NH4+), SO2, O3, C6H6 vapours, Hg, volatile phenols, Cl2, etc.

The particulate forms are: PM10 and PM2.5 particulate matter, heavy metals with toxic effect (Pb, Ni, Cd, As), polycyclic aromatic hydrocarbons PAHs, etc.

Atmospheric pollutants have a negative effect on the plants; they can have direct toxic effects, or indirectly by changing soil pH followed by solubilization of toxic salts of metals like aluminum. The particulate matters have a negative mechanical effect. They cover the leaf blade reducing light penetration and blocking the opening of stomata. These impediments influence strongly the process of photosynthesis which rate declines sharply.

Explanation:

Answer:

A More air pollution because there are fewer trees to take in carbon dioxide

C Fewer birds and other wildlife because they have fewer places to live

Explanation:

I took the test on A P E X

Answer: temperature, Stp

Explanation:

The calculation for standard temperature and pressure has been referred to as STP.

The mass-volume and volume-mass, has been the measurement of the concentration of the solution.

The mass-volume has been the measurement of mass of sample in the volume of solution. The volume by mass has been the measurement of the volume of solute to mass of solution.

The measurement has been performed with the standard conditions of temperature and pressure.

The standard temperature has been 273.5 K and standard pressure has been 1 atm. These temperatures and pressure has been referred to as STP.

Thus, the calculation for standard temperature and pressure has been referred to as STP.

Learn more about standard conditions, here:

https://brainly.com/question/2142674

Answer:

The 500kg boulder

Explanation:

Answer:

The general trend is for ionization energy to increase moving from left to right across an element period. Moving left to right across a period, atomic radius decreases, so electrons are more attracted to the (closer) nucleus.

Explanation:

Brainliest plz

Answer:

Ionization energy increases across the period and decreases down the group.

Answer: A hydrate is found to have the following percent composition: 48.8% MgSO4 and 51.2% water.

Explanation:

i dont know

Answer:

42.07%

Explanation:

Molar mass of Na3PO4 = 23×3 + 31 +16×4

= 69+ 31+64= 164 g/mol

Mass of Na in this compound is 69

Percentage of sodium in sodium phosphate = 69/ 164×100

Percentage of Na = 42.07%

Answer: An atom with 6 protons, 5 electrons, and 7 neutrons

Explanation: In this case, neutrons do not matter as they have a charge of 0, or no charge. A proton has a charge of +1 and an electron has a charge of -1. Since there are 6 protons, the total charge of the protons would be +6. Since there are 5 electrons the total charge of the electrons would be -5. +6 - 5 would result in a charge of +1. This means that this atom would have an overall charge of + 1. Basically, if there is one more proton than electron, then the overall charge of the atom will be +1 but if there is one more electron than proton, then the overall charge of the atom will be -1.

Answer:

The weight changes, but his or her mass does not.

Explanation:

The true statement from the given choices about an astronaut traveling from planet to planet is that the weight changes but his or her mass does not.

This is due to the difference in acceleration due gravity from one planet to the other.

Gravity from one planet to the other differs significant and so is the weight.

Answer:

Titanium is another metal that's commonly used in aerospace engineering. It's strong, lightweight, Aluminum isn't the strongest metal, but it maintains a perfect balance of strength and low weight that make airplanes fly

Explanation:

vote mee as the brainliest

Answer:

it weight were so thin

explanation

With a weight roughly a third lighter than steel, it allows an aircraft to either carry more weight, or become more fuel efficient. High Strength — Aluminum's strength allows it to replace heavier metals without the loss of strength associated with other metals, while benefitting from its lighter weight

Answer: A. Cows

E. Fertilizer

Explanation:

Answer:

Look at the properties of Oxygen and Silicon - the two most abundant elements in the Earth's crust - by clicking on their symbols on the Periodic Table.

Explanation:

Answer:

D. silicon and oxygen

Explanation:

The most abundant elements on the earth's crust are silicon and oxygen. Silicon and oxygen forms a wide range of silicate minerals they are found in the crust.

There are many silicates which are derived from the basal units of silicon and oxygen combining together. Other atoms or elements then combines with the silicate framework.

Oxygen is about 46% abundant in the crust whereas silicon takes about 28% to be the second most abundant element on the crust.

Silicate minerals abounds in rocks and within the soil.

Answer:

the heat from the sun makes the water molecules move faster and faster, until they move so fast they escape as a gas.

Explanation:

please tell me if I'm wrong

A.

Reason: cuz i need points noob

Answer:

794.96 kilojoules

Explanation:

multiply 190 by 4.184

There are 0.798 kilojoules an individual must consume when he/she takes a snack that has 190 Calories.

One calorie may be defined as a unit for measuring heat wjhich is equivalent to the amount of heat required to increase the temperature of one gram of water one degree Celsius.

According to the question,

The amount of calories a snack contains = 190 calories

Now, you should be required to convert calories into Joules.

1 calorie ≅ 4.2 Joules.

190 calories = 190 × 4.2 = 798 Joules.

Now, according to the conversion factor, 1 kilojoule = 1000 joules

∴ 798 Joules = 798/1000 = 0.798 kilojoules.

Therefore, there are 0.798 kilojoules an individual must consume when he/she takes a snack that has 190 Calories.

To learn more about Calories and Joules, refer to the link:

https://brainly.com/question/22066066?source=archive

#SPJ2

Answer:

36°C

Explanation:

Given parameters:

Mass of aluminum = 725g

Quantity of heat  = 2.35 x 10⁴J

Unknown:

Temperature change  = ?

Solution:

To solve this problem, we simply use the expression below:

  The quantity of energy is given as:

          Q  = m C Δt

Q is the quantity of energy

m is the mass

C is the specific heat capacity of aluminum  = 0.9J/g°C

Δt is the change in temperature

  The unknown is Δt;

             Δt  = [tex]\frac{Q}{mc}[/tex]    = [tex]\frac{2.35 x 10^{4} }{725 x 0.9}[/tex]    = 36°C

Answer:

Explanation:

B I got it right

Answer:

B. The ball will gain kinetic energy, and the racket will lose kinetic

energy

Explanation:

Answer:

Three

Explanation:

Nitrogen and phosphorus are on the same group in the periodic table. Elements in the same group have similar chemical properties. This is because of the number of valence electrons that they share among each other.

 The valence electrons are the outermost shell electrons found within an atom.

Nitrogen and phosphorus can both be found on the fifth group on the periodic table.

Their oxidation state is:

Since phosphorus bonds with 3 hydrogen atoms, nitrogen will also do the same.

Answer:

Hi - First you need to determine whether there is a metal or no and from there there are certain rules in order to name the compound. Here is a flowchart to try and help.

Answer:

convection

Explanation:

Extensive properties, such as mass and volume, depend on the amount of matter that is being measured. ... Both extensive and intensive properties are physical properties, which means they can be measured without changing the substance's chemical identity

Answer:

See explanation

Explanation:

The third law of thermodynamics states that "the entropy of a perfect crystal of a pure substance approaches zero as the temperature approaches zero" (Wikipedia).

One example of the third law of thermodynamics has to do with steam. Steam is gaseous water. Since it is a gas, its molecules are free to move around therefore its entropy is high. When the temperature of the steam is decreased below 100 degrees, the molecules of steam loose energy and turn into liquid water and do not move as freely as they did in the gaseous state. If the temperature is further decreased to yield ice at zero degrees, the molecules of water are "frozen" in their positions and the entropy of the system decreases to zero.

Also, the ions in ionic crystal solids move around when the substance is in solution or in molten state hence the substance conducts electricity. When the ionic substance is in solid state, the ions do not move about and the entropy of the solid system tends towards zero.

That would be the skeletal system, hope this helps ^^

The molality of a solution : m = 0.33 mol/kg

Given

2 moles of NaOH in 6 kg  of water

Required

The molality

Solution

Molality shows how many moles are dissolved in every 1000 grams of solvent.

m = n x (1000/p)

m = Molality

n = number of moles of solute

p = solvent mass (grams)

Input the value :

solute : NaOH

solvent : water

m = 2 moles : 6 kg

m = 0.33 mol/kg

Answer: here is your answer

Explanation:

The oxygen family consists of the elements that make up group 16 on the periodic table: oxygen, sulfur, selenium, tellurium, and polonium. These elements all have six electrons in their outermost energy level, accounting for some common chemical properties among them.

Answer:

they all have 6 valence electrons

Explanation:

all elements in group 16 have 6 valence electrons