Answer:
trigonal pyramidal
Explanation:
In NF3, the nitrogen atom is sp3 hybridized. Now we must remember that according to the VSEPR theory, the number of electron pairs in the valence shell of the central atom in a molecule determines its shape.
Here, the nitrogen atom is the central atom and its outermost shell is surrounded by four electron pairs - one lone pair and three bond pairs. This means that it has a tetrahedral electron pair geometry.
However, due to the lone pair, the three fluorine atoms are arranged in a trigonal pyramidal geometry. Hence the correct shape of the molecule is trigonal pyramidal.
A 0.85% saline solution is: a.8.5 mL of saline added to 91.5 mL of water b.85 g of NaCl made up to 1,000 mL of water c.0.85 g NaCl made up to 100 mL of water d.8.5 g NaCl in 100 mL of water
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.
The initial temperature of a bomb calorimeter is 28.50°C. When a chemist carries out a reaction in this calorimeter, its temperature decreases to 27.45°C. If the calorimeter has a mass of 1.400 kg and a specific heat of 3.52 J/(gi°C), how much heat is absorbed by the reaction?
Use q equals m C subscript p Delta T..
140 J
418 J
1,470 J
5,170 J
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.
The temperature of an object is directly related to
A.
the mass of the object.
B.
the motion of its particles.
C.
the potential energy of its chemical bonds.
D.
the volume of the object.
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.
How many moles are there in 1.68 * 10 ^ 24 molecules of nitrogen dioxide?
Answer:
2.79 molesExplanation:
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
2.79 molesHope this helps you
Which statement is true of all chemical reactions? They can go in just one direction. They can go in just one direction. They occur only in science labs. They occur only in science labs. They break and reform bonds. They break and reform bonds. They create new elements.
Answer:
They break and reform bonds
Explanation:
Chemical reactions basically refer to the transformation of a substance (reactant) to another substance (products).
So we have;
Reactant --> Product
They can go in just one direction.
This option is wrong, because there are reversible reactions which can go in both directions. That is reactants reactants to form products and products react to form reactants.
They occur only in science labs.
This is wrong because chemical reactions occur in our day to day activities. An example is rusting.
They break and reform bonds.
This option is correct. There is breaking of bonds in the reactants and forming of new bonds in the products.
They create new elements
Atoms or elements are not created nor destroyed in chemical reactions so this option is wrong.
4. What gives blood its red color?
a. hemoglobin
O
b. red blood cells
O
c. platelets
d. plasma
Answer:
the best answer would be A
Explanation:
cause it contains a red colored compound.
What historical event of commercial interest triggered investigation in the science of steam?
Answer: Photosynthesis
Explanation:
i will give brainliest
Which statement best describes the direction of force shown by the magnetic
field lines around a bar magnet?
A. Away from both the magnet's north and south poles
B. Toward both the magnet's north and south poles
C. From the magnet's north pole to its south pole
D. From the magnet's south pole to its north pole
Answer:
I believe the amswer is a hope this helps
Answer:
c
Explanation:
hope you can redo it to get it right
How many neutrons are present in an atom of
Which force saves the atom by emitting particles from the nucleus
Answer:
nuclear force
Explanation:
Who do you think we (humans) are more related to bats, or chickens?
Answer:
prolly chickens
disadvantages of Mendeleev's periodic table
Answer:
Various limitations of Mendeleev's periodic table are:-
Position of hydrogen - he couldn't assign a correct position to hydrogen as it showed properties of both alkali and halogens .
Position of isotopes - he considered that the properties of elements are a function of their atomic masses. Hence isotopes of a same element couldn't be placed.
In the d-block , elements with lower atomic number were placed before higher atomic number.
Explanation:
look.............................................
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.
What is a radio wave?
Answer:
Radio waves are a type of electromagnetic radiation best-known for their use in communication technologies, such as television, mobile phones and radios.
99% 1H
0.8% 2H
0.2% 3H
Average Atomic Mass = [answer] amu
PLEASE HELP ME
Answer: 1.01 atomic mass units or amu
Explanation:
. Now Sara comes along, and she is the exact same size as you. However, she is even stronger than you are! When she pulls you in the wagon, she pulls with a greater force than when you pull her. Now who is in the wagon when it has the greatest acceleration? Explain, using Newton's second law. Sara would win because she is stronger but we have the same force.
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.
One isotope of a nonmetallic element has mass num- ber 127 and 74 neutrons in the nucleus. The anion derived from the isotope has 54 electrons. Write the symbol for this anion.
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⁻
which statements are wrong about atoms
Answer: Atoms are not able to exist independently
Explanation:
Write the name of the covalent compound ON.
Answer:
the answer is oxygen mononitride
The temperature of a 9.0 g sample of glass changed from 20 to 50 when it absorbed 680 J of heat. What is the specific heat of this glass sample?
Answer:2518.5J/kg/K
Explanation:
Sarah wants to know where in her garden chamomile would grow the best. She thinks chamomile will grow best in the corner of the garden that gets the most sunlight. To test her hypothesis, she decides to plant several groups of chamomile in her garden as an experiment.
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:
Haley is trying to pull an object upward. The below forces are acting on the object.
Fp= 5500 N
Fg= 6000 N
Which represents the net force?
← 500 N
→ 500 N
↑ 500 N
↓ 500 N
Explanation:
it's answer is last
hope it helps you
↓ 500 N represents the net force as the force is acting in downward direction.
What is force?
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
The specific heat of aluminum is 0.88 J/g°C. How many joules will it take to make the temperature of a 50. g nugget go up from 20.°C to 70.°C?
Answer:
2200J
Explanation:
Given parameters:
Specific heat of aluminum = 0.88J/g°C
Mass of nugget = 50g
Initial temperature = 20°C
Final temperature = 70°C
Unknown:
Quantity of heat required for the heating = ?
Solution:
To solve this problem, we use the expression below;
H = m c Δt
H is the quantity of heat
m is the mass
c is the specific heat capacity
Δt is the change in temperature
H = 50 x 0.88 x (70 - 20) = 2200J
What is the volume of 2 moles of He at STP?
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:
(0)A mixture of dihydrogen and dioxygen at one bar pressure contains 70% by weight of dioxygen. Calculate the partial pressure of dioxygen.
a (ii)Calculate the volume occupied by 8.8 g of CO2 at 31.1°C and 1 bar pressure. R = 0.083 bar L K-1 mol-1
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
Which of the following is considered the first receiver for the nicotine in a smoking person?
1.left atrium
2.right atrium
3.left ventricle
4.right ventricle
Answer:
i think right artrium but not full aure
One characteristic that salt water and sugar-water have in common is, at room temperature, they are
a)gases
b)solids
c)mixtures
d)elements
Answer:
The one thing they have in common is that They are mixtures
Answer:
they are both mixtures
Explanation:
Which of the following elements has the highest atomic radius, Sr or Cu
Answer:
Sr or Strontium
Explanation:
sr: strontium has atomic radius of 255pm
cu: copper has an atomic radius of 128pm
they teach you in chem how to do it based off the chart but I don't remember that method
which best explains why estuaries are an important habit for many Marine organisms in comparison to the open ocean?
A) there is less food in the estuaries
B) there are more predators in estuaries
C) there is more salt available in estuaries
D) there are more nutrients available in estuaries
which best explains why estuaries are an important habit for many Marine organisms in comparison to the open ocean?
Answer:-there are more nutrients available in estuaries
Extra information:-Open ocean:-The Open ocean is also known as pelagic zone.It is the area of the ocean which is outside of coastal areas. The open ocean lies over the continental shelf. The seafloor is not included in the open ocean.What would you observe in the following cases:
(1) Sodium and potassium are placed in hot water
(ii) Burning magnesium is introduced into steam?
dium and iron with water
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