Halfnium has three isotopes; 74% Hf-180, 17% Hf -176, and 9 % Hf- 177. Calculate the mass of Halfnium.

Answer:

SBr2: Electron geometry-tetrahedral; molecular geometry-trigonal pyramidal

PI4+: Electron geometry-tetrahedral; molecular geometry-tetrahedral

IBr2−: Electron geometry- Trigonal bipyramidal ; molecular geometry- linear

Explanation:

In SBr2, the molecule is of the structure type AX2E2 hence it is based on a tetrahedron but have two lone pairs of electrons hence the molecular geometry is trigonal pyramidal.

PI4+ has four electron domains and all of them are bond pairs hence both electron geometry and molecular geometry are both tetrahedral.

IBr2- is of the structure type AX2E3 hence it is based on a trigonal bipyramd and has a linear molecular geometry.

2)

SiF4 has a tetrahedral molecular and electron domain geometry because the central atom(Si) has no lone pairs.

SeF4 has a trigonal bipyramidal electron geometry with the structure AX4E. Its molecular geometry is See-saw since it has one lone pair of electrons that causes a deviation from its ideal trigonal bypyramidal geometry.

XeF4 has  an octahedral electron domain geometry and the molecule is AX4E2. The two lone pairs are positioned above and below the plane of a square hence the molecule is square planar.

Answer:

its natural gas because i had something like this

Explanation:

The renewable energy sources, such as biomass, geothermal resources, water, wind, etc. are called the natural resources. These can be converted into clean and usable energy. The correct option is D.

The energy which is derived from the natural sources which are replenished at a higher rate than they are consumed is defined as the Renewable energy. The renewable energy generating produce lower emissions than burning the fossil fuels.

The word biomass refers to the organic plant matter which is converted into fuel and used as an energy source. The biomass fuel is considered as an important renewable and sustainable source of energy. It is used for the production of electricity.

The organic materials like wood, agricultural wastes, etc. acts as the excellent sources to produce biomass fuel. It is possible to burn the biomass fuel directly and later converted into methane and ethanol biofuels.

Thus the correct option is D.

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Answer:

Organisms and humans depend on each other to get by. Environmental science is important because it enables you to understand how these relationships work.

For example, humans breathe out carbon dioxide, which plants need for photosynthesis. Plants, on the other hand, produce and release oxygen to the atmosphere, which humans need for respiration.

Animal droppings are sources of nutrients for plants and other microorganisms. Plants are sources of food for humans and animals. In short, organisms and humans depend on each other for survival.

Explanation:

Answer:

7.5%

Explanation:

I just know it's that

Answer:

We are given that there is 95% ethanol by mass in rectified spirit

so, we can say that in a 100g sample, we have 95 grams of ethanol and 5 grams of water

we will find the number of moles of ethanol and water in 100g solution of rectified spirit and use that to calculate the mole fraction

Moles of Ethanol:

Molar mass of ethanol = 46 grams / mol

Number of moles = Given mass / molar mass

Number of moles = 95 / 46

Moles of Ethanol = 2 moles (approx)

Moles of Water:

Molar mass of water = 18 grams per mol

Number of moles = Given mass / molar mass

Moles of water = 5 / 18

Moles of water  =  0.28 moles   (approx)

Mole Fractions:

Mole fraction of a specific compound is the number of moles of that compound divided by the total number of moles in the solution

Mole fraction of Ethanol:

Moles of ethanol / (moles of ethanol + moles of water)

2 / (2 + 0.28)

2 / (2.28) = 0.9 (approx)

Mole fraction of Water:

Moles of water / (Moles of ethanol + moles of water)

0.28 / (2 + 0.28)

0.28 / (2.28) = 0.1 (approx)

Answer:

The answer is D - Atom

The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the atom.

An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.

The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.

Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.

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Answer:

C

Explanation:

Hope this helps :)

Answer: The answer is the ''The moon is always lit up by the sun for us to see.''

Explanation: The moon is directly illuminated by the sun.

Answer:

Inductive reasoning

Explanation:

Inductive reasoning is based on making broad generalizations from specific observations. We draw conclusions from the data we have. This is the opposite of deductive reasoning, which starts with a general statement and aims to reach a specific conclusion.

Based on this, we can conclude that, if an investigator uses their knowledge, training, experience, and expertise to reach a conclusion, they are using inductive reasoning.

Answer: The particles are moving fast but close together.

Answer:

its in the explanation.

Explanation:

1.In liquids, particles are quite close together and move with random motion throughout the container. Particles move rapidly in all directions but collide with each other more frequently than in gases due to shorter distances between particles.

2.It assumes the shape of the part of the container which it occupies particles can move/slide past one another.

Hope this helps. :)

Answer:

POTASSIUM

Explanation:

2 8 8 1________ 1A

Answer:

Linear molecule with two domains

Explanation:

Answer:

70.88 mL volume of 1.27 M of HCl is required.

Explanation:

Given data:

Initial volume = ?

Initial  molarity =  1.27 M

Final volume = 197.4 mL

Final molarity = 0.456 M

Solution:

Formula:

M₁V₁ = M₂V₂

Now we will put the values in formula.

1.27 M × V₁ =  0.456 M × 197.4 mL

V₁ = 0.456 M × 197.4 mL/1.27 M

V₁ = 90.014M.mL/1.27 M

V₁ = 70.88 mL

70.88 mL volume of 1.27 M of HCl is required.

Answer:

this atom has nine electrons

Answer:Two Main Types of Pure Substances

Elements and compounds are the two types of pure substances. Examples of common elements include carbon, nitrogen and hydrogen. They consist of one type of atom and cannot break down into something else. Every pure carbon substance, for example, has the same particles in it.

Explanation:I think

Answer:

The mass of sodium chloride in the mixture is 18.75%

Explanation:

Here, we want to calculate the percentage of sodium chloride in the mixture.

The total mass of the mixture is 52 g + 12 g = 64 g

So the percentage mass of sodium chloride will be;

mass of sodium chloride/ Total mass * 100%

That will be: 12/64 * 100 = 18.75%

Answer:

KOH(aq) + HCI(aq)  ----->  KCI(aq )+ H2O

base          acid               salt          water

hope this helps :)

Explanation:

The formula for the aqueous salt produced when hydroiodic acid is neutralized by potassium hydroxide is KI. The neutralization reaction between hydroiodic acid and potassium hydroxide is given below.

HI(aq) + KOH(aq) → KI(aq) + H2O(l)

The reaction between acid and base to form salt and water is called neutralization reaction.

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Answer:

Required heat = 2,259.36 N (approx)

Explanation:

Given:

Mass = 135 g

Specific heat (c) =4.184 J/gC

Change in temperature ΔT = 27-23 = 4 c

Find:

Required heat

Computation:

Q = mcΔT

Q = (135)(4.184)(4)

Required heat = 2,259.36 N (approx)

The heat transferred by the chemical reaction to the reservoir of a calorimeter containing 135 g of dilute aqueous solution is 2259.36 J

To solve this question, we'll begin by calculating the change in the temperature of the reservoir. This can be obtained as follow:

Initial temperature (T₁) = 23 °C

Final temperature (T₂) = 27 °C

ΔT = T₂ – T₁

ΔT = 27 – 23

Finally, we shall determine the heat transferred to the reservoir.

Change in temperature (ΔT) = 4 °C

Mass (M) = 135 g

Specific heat capacity (C) = 4.184 J/gºC

Q = MCΔT

Q = 135 × 4.184 × 4

Therefore, the heat transferred by the chemical reaction to the reservoir of a calorimeter containing 135 g of dilute aqueous solution is 2259.36 J

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Answer:

valence electrons

Explanation:

The valence electrons are the outer most electrons and the principal energy level in which they belong will vary for .

The chemical element which contains four (4) electrons in its third and outer main energy level is: Silicon (Si).

An electron shell can be defined as the outermost shell of an atom of a chemical element around the atomic nucleus.

Hence, an electron shell is an orbital that is typically accompanied by electrons around the nucleus of an atom.

A sublevel is also referred to as an orbital and it can be defined as an energy level that is associated with the electrons found outside the atomic nucleus.

In Chemistry, there are four main (4) types of sublevel and these are:

In the third (3rd) energy level, there are only three (3) sublevels and these are; s, p and d sublevels.

Silicon is a chemical element that is found in group (4) of the periodic table because it has four (4) electrons in its third and outermost shell.  

In its ground state, Silicon (Si) contains the following number of electrons:

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Answer:

6.02 × 10²³ atoms Cl₂

Explanation:

Avagadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Step 1: Define

1.00 mol Cl₂ (g)

Step 2: Use Dimensional Analysis

[tex]1.00 \hspace{3} mol \hspace{3} Cl_2(\frac{6.02(10)^23 \hspace{3} atoms \hspace{3} Cl_2}{1 \hspace{3} mol \hspace{3} Cl_2} )[/tex] = 6.02 × 10²³ atoms Cl₂

Answer: 0 I think

Explanation:

pretty sure its zero because  i learned it last year but im in middle school so you might want to look it up.

Answer:

seafloor spreading

Explanation:

i took the test

Answer: here is your answer

Explanation: You are visiting your Grandmother and notice that she is eating a balanced diet, taking vitamins, getting the proper amount of sleep and is not overweight. Despite her healthy lifestyle, she appears run down and tired. You realize that it's due to her lack of physical activity. Write a convincing letter to your grandma explaining the benefits of participating in regular physical activity.

Answer:Because plastic products are durable, they can last for a long time. This makes them affordable because they do not have to be replaced often. On the other hand, the popular use of plastics means that many plastics are thrown away. Plastics litter the ocean, causing harm to marine birds and mammals. Plastic breaks down into plastic dust, which can last for up to a thousand years.

^^^^^copy and paste this part^^^^^

Explanation:Plastic is he hardest material to break down with harm to sea life and land life they may be affordable but costly to the environment.

Answer:

6 protons 8 neutrons 5 electrons

Explanation:

protons are blue neutrons are red electrons are green