Which of the following is an indication of a physical change?
O A. The formation of a new substance
O B. Giving off a smell
O C. A change in the shape of a substance
O D. The production of gas and heat
Answer:
A change in the shape of a substance
Explanation:
Because when ths shape of a sunstance changes , its physical appearance changes .A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.
When 0.25 moles of NH3 are produced according to the reaction below, how many moles of H2 must have reacted?
N2 + 3 H2 --> 2 NH3
O 1.5 moles H2
O 0.38 moles H2
O 0.25 moles H2
O 0.17 moles H2
Answer:
Explanation:
by stoichiometry
nNH3/2=nH2/3
0.25/2=nH2/3
nH2=0.25×3/2
nH2=0.375 mol
so its 0.38 mol
Answer:
I have this quiz rn I will try 0.38 if it is right I’ll edit this and say that
Explanation:
Please Help!!!
Which of the following is not a good indication that a chemical change has occurred?
A. The formation of gases
B. A change in color
C. A scratched surface
D. The release heat or light
Answer:
C.
Explanation:
Why is NCl3 not soluble in water?
Answer:
Explanation:
NCl3 does not dissolve in water because it is a nonpolar molecule which is different with water. NCl3 is nonpolar due to the difference in electronegativities between 3 atoms of Cl and 1 atom if N2.
Answer:
A polar solute dissolves into a polar solvent and a non-polar compound dissolves into a non-polar solvent, this rule is known as "like dissolves like".
Please help me how do i solve this
Answer:120
Explanation:2gfdxxfgngfnf
How many grams are equal to 0.11 mole of copper(I) chromate?
Mass of Copper(I) chromate( CuCrO₄) = 19.75 g
Further explanationThe mole is the number of particles contained in a substance
1 mol = 6.02.10²³
Moles can also be determined from the amount of substance mass and its molar mass
[tex]\tt \large{\boxed{\bold{mol=\dfrac{m(mass)}{MW(molecular~weight)}}}[/tex]
0.11 mole of Copper(I) chromate( CuCrO₄) ⇒ MW=179.54 g/mol, so mass :
[tex]\tt mass=mol\times MW\\\\mass=0.11\times 179.54\\\\mass=19.75~g[/tex]
Hydrogen bond is not formed by 1) oxygen 2) nitrogen 3) chlorine
PLEASE HELP!!!
Answer:
Input work is the work done on a machine as the input force acts through the input distance. This is in contrast to output work which is a force that is applied by the body or system to something else. Output work is the work done by a machine as the output force acts through the output distance.Jan 15, 2020 bahsgsh bvshgs d hg
Which of the following subatomic particles are found surrounding the nucleus and have a negative charge?
F negatrons
G neutrons
H protons
J electrons
Answer:
J electrons
Explanation:
Electrons are the negatively charged subatomic particles that surrounds the nucleus of an atom.
Electrons occupy the bulk volume of an atom. These particle was discovered by J.J ThomsonThey found orbiting the extra-nuclear space of every atom. The nucleus is made up of protons and neutrons.1. What part of the human body has the same role as the power source in a computer?
2.What part of the human body has the same role as the keyboard or the mouse on a computer?
Answer:
The heart
Hand
Explanation:
The part of the human body that has the same role as the power source in a computer is the heart. A power source in a computer provides energy that powers the whole system.
The human heart provides the pumping action for the circulatory system. Just like current passes through wires in a computer by energy from the power source, the human heart pumps blood throughout the body in a like manner. Without the pumping action of the heart, the human body is dead.Also, keyboard and mouse are input devices. They are used to give instruction and perform certain tasks on the computer system.
The human body can also carryout tasks by using the hand. Objects are moved from one place to another just as you drag an icon using the mouse. We type word processors using information from the keyboard, also, we are able write using pen on paper.An isotope of Cesium -137 has a half-life of 30 years. If 1.0 g of Cesium – 137 disintegrates over a period of 60 years, how many grams of Cesium- 137 would remain?
Answer:
Explanation:
Radioactive decay follows the equation:
Ln [A] = -kt + ln [A]₀
Where [A] is amount of isotope after time t: Our incognite,
k is rate constant: ln 2 / Half-life = 0.0231 years⁻¹
t are 60 years
[A]₀ is initial amount of isotope: 1.0g
Replacing:
Ln [A] = -kt + ln [A]₀
Ln [A] = -0.0231 years⁻¹*60 years + ln 1.0g
ln [A] = -1.386
[A] = 0.25g
Momentum is mass times
A. acceleration
B. velocity
C. distance
B. velocity
This is the answer
What color are the stars on the diagram with the lowest surface temperatures?
Answer:
red supergiants is the answer
After pollen grows on a tube down the style,___
Answer:
as soon as the pollen reaches the stigma after the pollen grain descends down the style when the pollen tube grows into the ovule when the seed germinates
Explanation:
How many moles of Cl2 are needed in order to produce 100.0 grams of FeCl3 given the following
equation: 2 Fe + 3 Cl2 → 2 FeCl3
B
T
Answer:
0.92moles
Explanation:
Given reaction:
2Fe + 3Cl₂ → 2FeCl₃
Mass of FeCl₃ = 100g
Unknown:
Number of moles of Cl₂ needed = ?
Solution:
To solve this problem, we work from the known specie to the unknown.
From the mass of the FeCl₃ given, we can solve for the number of moles of the unknown.
Number of moles of FeCl₃;Number of moles = [tex]\frac{mass}{molar mass}[/tex]
Molar mass of FeCl₃ = 56 + 3(35.5) = 162.5g/mol
Number of moles = [tex]\frac{100}{162.5}[/tex] = 0.62mole
From the reaction expression;
2 mole of FeCl₃ is produced from 3 moles of Cl₂
0.62 mole of FeCl₃ will be produced from [tex]\frac{0.62 x 3}{2}[/tex] = 0.92mole
The number of moles of Cl₂ = 0.92moles
how many sig figs are in 0.0093
Answer:
there are two significant figures
Explanation:
Answer:
there are two
Explanation:
because the zeros dont count
Niels Bohr’s model of the atom helped to explain
Answer:
a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits.
Explanation:
Help me with homework.
The chemical equation is said to be balanced if the number of atoms in the reactants and products is the same
Further explanationEquation balanced ⇒ total number of atoms in reactants(on the left)= total number of atoms in products(on the right)
H₂+O₂---> H₂O
Reactants : H₂, O₂
Products : H₂O
not balanced
H₂O₂ ---> H₂O+O₂
Reactants : H₂O₂
Products : H₂O, O₂
not balanced
Na+O₂ ---> Na₂O
Reactants : Na, O₂
Products : Na₂O
not balanced
N₂+H₂ ---> NH₃
Reactants : N₂, H₂
Products : NH₃
not balanced
P₄+O₂---> P₄O₁₀
Reactants : P₄, O₂
Products : P₄O₁₀
not balanced
Fe+H₂O ----> Fe₃O₄ + H₂
Reactants : Fe, H₂O
Products : Fe₃O₄
not balanced
1. Why is soil erosion relatively less in dense forests as compared to barren, open fields?
Because the deep roots of big trees hold the soil and don't let it slip away simply by rain or wind.
Answer:
the roots of the trees keep the soil in place opposed to a barren landscape that has little to no plants to keep the soil in place
hope this helps (╹ڡ╹ )
Which of the following best describes a hypothesis?
A. An explanation that is supported by scientific data
B. A proven explanation for experimental results
c. A possible answer to a scientific question
D. A question about the natural world
please help i will give brainliest
An independent variable is....
A: What we measure
B: What we change
C: What stays the same
D: What we conclude
Answer:
B - What we change
Explanation:
Dependent Variable - What we measure
Control Variable - what stays the same
Conclusion - what we conclude
Hope this can Help!
:D
Use the model to answer the question.
Which element symbol actually represents the model?
Plz answer
Answer:
B
Explanation:
Boron has 5 protons.
paragraph on water cycle
Answer:
The water cycle or hydrologic is a continuous cycle where water evaporates, travels into the air and becomes part of a cloud, falls down to earth as precipitation, and then evaporates again. ... These areas are usually close to oceans or large bodies of water that allow more water to evaporate and form clouds.
Explanation:
How to do this question plz answer me
Answer:
dissolved
Explanation:
The figure shows sodium chloride is in solution. It gets that way by being dissolved.
If 150 G of war started burning 300 G of where as was left behind how many grams of CO2 gas is released
Answer:
geruow0irghvn3p0unhie0ghik
Explanation:
Can someone help? Ill give brainliest!
Directions: count each side of the reaction then Circle yes or no if it follows the law of conservation of mass
Answer:
Explanation:
before the reaction you have K=2 and Cl=4
after the reaction K=2 and Cl=2 so it does not follow the law of conservation
Which of the following most likely happens when thermal energy is removed from a chemical reaction?
Answer:
fewer collisions occur between particles or lowering the temperature
Explanation:
We can change the substance chemically by
freezing it.
True or false
Directions: Read through each scenario and identify the independent variable, dependent variable, and the control.
Question 1
1 pts
Rob is in charge of waxing the floor at the local mall. He wants to test a new brand of floor wax called
Squeaky Clean. Rob waxes 20 floor tiles with Squeaky Clean and 20 tiles with the original wax brand.
After one week he counts the number of scratches on the floor. What is the independent variable?
number of floor scratches
brand of floor wax
20 tiles with original brand wax
Answer:
The correct answer is - brand of floor wax.
Explanation:
The independent variable is the variable or the factor in an investigation which is manipulated or change in the experiment and affects the dependent variable and produces a various result.
In this investigation, there are different brands of the floor was are the independent variable as they are changed to see the effect on the scratches on the floor on 20 tiles for each brand.
What will happen to the flow of blood in blood vessels (pulse) if heart beat rate increase
Answer:
"Low levels of the hormone epinephrine, also called adrenaline, cause blood vessels to relax and widen. High levels of this same hormone, along with the hormone norepinephrine, cause the blood vessels to narrow and the heart rate to rise, increasing blood pressure."
Explanation:
Help please If there are 10 moles of HCl gas occupying 15L at 350°C, what is the pressure? Be sure to show the setup and
the final answer and unit.
Show Your Work
Answer:
P = 34.1 L
Explanation:
Given data:
Number of moles = 10 mol
Volume occupy = 15 L
Temperature = 350°C
Pressure of gas = ?
Solution:
The given problem will be solve by using general gas equation,
PV = nRT
P= Pressure
V = volume
n = number of moles
R = general gas constant = 0.0821 atm.L/ mol.K
T = temperature in kelvin
Now we will convert the temperature.
350+273 = 623 K
by putting values,
P×15 L = 10 mol ×0.0821 atm.L/ mol.K ×623 K
P = 511.48atm.L/15L
P = 34.1 L