Answer
b.
Explanation:
variable means change bro
the internacional system of units is based on ?
Answer:
The international system of units is basic on 7 units.
Hope it helps you.Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Answer:
bubble and foam!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
calculate the number of each atom in 2.5 gram of caco3
Answer:
[tex]2.5\; \rm g[/tex] of [tex]\rm CaCO_{3}[/tex] would contain:
Approximately [tex]1.5 \times 10^{22}[/tex] calcium atoms (approximately [tex]0.025\; \rm mol[/tex],)Approximately [tex]1.5 \times 10^{22}[/tex] carbon atoms (approximately [tex]0.025\; \rm mol[/tex],) andApproximately [tex]4.5 \times 10^{22}[/tex] oxygen atoms (approximately [tex]0.075\; \rm mol[/tex].)Explanation:
Look up the Avogadro constant: [tex]N_{\rm A} \approx 6.022 \times 10^{23}\; \rm mol^{-1}[/tex].
For example, "[tex]1\; \rm mol[/tex] of carbon atoms" would contain [tex]N_{\rm A}[/tex] carbon atoms (approximately [tex]6.022\times 10^{23}[/tex]) by definition.
Look up the relative atomic mass of carbon, calcium, and oxygen on a modern periodic table:
Calcium: [tex]40.078[/tex].Carbon: [tex]12.011[/tex].Oxygen: [tex]15.999[/tex].In other words, the mass of [tex]1\; \rm mol[/tex] of calcium atoms would be [tex]40.078\; \rm g[/tex]. The mass of [tex]1\; \rm mol\![/tex] of carbon atoms would be [tex]12.011\; \rm g[/tex], and the mass of [tex]1\; \rm mol \!\![/tex] of oxygen atoms would be [tex]15.999\; \rm g[/tex].
As the formula [tex]\rm CaCO_{3}[/tex] suggests, every formula unit of this ionic compound includes one calcium atom, one carbon atom, and three oxygen atoms. The formula mass of [tex]\rm CaCO_{3}\![/tex] would give the mass of every mole of [tex]\rm CaCO_{3}\!\![/tex] formula units.
Calculate the formula mass of [tex]\rm CaCO_{3}[/tex] from the relative atomic mass data:
[tex]\begin{aligned} & M({\rm CaCO_{3}}) \\ =\; & 40.078\; \rm g \cdot mol^{-1} \\ & + 12.011\; \rm g \cdot mol^{-1} \\ & + 3 \times (15.999\; \rm g \cdot mol^{-1}) \\ =\; & 100.086\; \rm g \cdot mol^{-1}\end{aligned}[/tex].
Calculate the number of [tex]\rm CaCO_{3}[/tex] formula units in that [tex]2.5\; \rm g[/tex] of this compound:
[tex]\begin{aligned}& n({\rm CaCO_{3}}) \\ =\; & \frac{m({\rm CaCO_{3}})}{M({\rm CaCO_{3}})} \\ =\; & \frac{2.5\; \rm g}{100.086\; \rm g \cdot mol^{-1}} \\ \approx\; & 0.025\; \rm mol\end{aligned}[/tex].
In other words, [tex]2.5\; \rm g[/tex] of [tex]\rm CaCO_{3}[/tex] would contain approximately [tex]0.025\; \rm mol[/tex] [tex]\rm CaCO_{3}\![/tex] formula units.
Again, there are one calcium atom, one carbon atom, and one oxygen atom in every [tex]\rm CaCO_{3}[/tex] formula unit. That approximately [tex]0.025\; \rm mol[/tex] [tex]\rm CaCO_{3}\![/tex] formula units would thus contain:
Approximately [tex]1 \times 0.025\; \rm mol = 0.025\; \rm mol[/tex] calcium atoms, Approximately [tex]1 \times 0.025\; \rm mol = 0.025\; \rm mol[/tex] carbon atoms, andApproximately [tex]3 \times 0.025\; \rm mol = 0.075\; \rm mol[/tex] oxygen atoms.Make use of the Avogadro constant to convert the numbers.
For example, the number of calcium atoms in that approximately [tex]0.025\; \rm mol[/tex] of calcium atoms would be:
[tex]\begin{aligned} & N({\text{calcium}) \\ = \; & n({\text{calcium}) \cdot N_{\rm A} \\ \approx \; & 0.025\; \rm mol \times 6.022\times 10^{23} \cdot mol^{-1} \\ \approx \; & 1.5 \times 10^{22} \end{aligned}[/tex].
Likewise, the number of carbon atoms in that approximately [tex]0.025\; \rm mol[/tex] of carbon atoms would be:
[tex]\begin{aligned} & N({\text{carbon}) \\ = \; & n({\text{carbon}) \cdot N_{\rm A} \\ \approx \; & 0.025\; \rm mol \times 6.022\times 10^{23} \cdot mol^{-1} \\ \approx \; & 1.5 \times 10^{22} \end{aligned}[/tex].
The number of oxygen atoms in that approximately [tex]0.075\; \rm mol[/tex] of oxygen atoms would be:
[tex]\begin{aligned} & N({\text{oxygen}) \\ = \; & n({\text{oxygen}) \cdot N_{\rm A} \\ \approx \; & 0.075\; \rm mol \times 6.022\times 10^{23} \cdot mol^{-1} \\ \approx \; & 4.5 \times 10^{22} \end{aligned}[/tex].
Hello please I need help
Am element has 18 electrons ,20 neutrons and a charge of -2.what is the mass number?..a.38 b.40 c.32 d.39
Answer:
Surely you must have a Periodic Table beside you....?
a=38
Explanation:
You gots Z=18, the atomic number, where Z is the number of nuclear protons. The number of protons defines the element....and thus we got calcium....
....and with 20 neutrons we got the 38Ca isotope....the which is rather short-lived...
Which substance is an element that is composed of molecules?
A. water (H2O)
B. methane (CH4)
C. hydrogen (H2)
D. helium (He)
Answer:
the answer is hydrogen which is B
The substance is an element that is considerably composed of molecules known as hydrogen (H2). Thus, the correct option for this question is C.
What is a Chemical element?A chemical element may be defined as a species of an atom that remarkably bears a specific number of sub-atomic particles in its structure. These elements are not further decomposed into smaller components in a chemical reaction.
H2 is also known as molecular hydrogen. It forms when two hydrogen atoms are significantly bonded to one another in order to give rise to a molecule. Water is not an element, it is a molecule. While methane is a chemical compound that possesses a chemical formula CH4. Helium (He) is a chemical element only.
Therefore, hydrogen is an element that is composed of molecules. Thus, the correct option for this question is C.
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calculate mass of MnO2 if 1 mole of KMnO4 completely burnt. 2KMnO4 -> K2MnO4+MnO2+O2
Answer: 80 grams
Explanation:
2KMnO4 -> K2MnO4+MnO2+O2
2 moles of KMnO4 would produce 1 mole of MnO2, so 1 mole of KMnO4 would produce 0.5 moles of MnO4. The molar mass of MnO4 is 160 g/mole. 1/2 mole of KMnO4 would therefore be (160 g/mole)*(0.5 moles) = 80 grams.
Neha and Reha are playing see-saw. Neha is sitting 60 cm away from the fulcrum and Reha is sitting 40 cm away from the fulcrum. Calculate the effort that Reha should apply to lift Neha. The weight of Neha is 360 N.
Answer:
Reha should apply 540 N to lift Neha.
Explanation:
L = 360 N
LD = 60 m
E =?
ED = 40m
NOW
L * LD = E * ED
360 *60 = E*40
21600/40 = E
540 N = E
I need help on this question plzzz
Answer:
76 ml
0.076 L
Explanation:
hope that helps
Answer:
76 for the first one at least I think
when two atoms share four valence electrons the shared electrons form a/an ____
Dieldrin is a pesticide that is effective in killing?
Answer:
fddoiiijjjjjjjhhggggrrddffgghuuiii
Illustrate the law of law of multiple proportions using the formation of SO2 and SO3 by sulphur and oxygen
As illustrated from law of multiple proportion, the mass of the oxygen which combined with a fixed mass of the sulphur is in simple whole number ratio of 2 is to 3 (2:3).
The law of Multiple proportion states that when two elements combine to form more than one compound, the mass of the second element, which combines with a fixed mass of the first element, will always be ratios of small whole numbers.
To illustrate the law of multiple proportion from sulphur and oxygen, we use the given compounds.
The reaction of oxygen with sulphur to form SO₂ and SO₃:
[tex]S \ + \ O_2 \ -----> SO_2\\\\2SO_2 \ + \ O_2 \ ---> \ 2SO_3[/tex]
atomic mass of oxygen = 16 g
atomic mass of sulphur = 32 g
In the formation of SO₂:mass of sulphur = 32 g and mass of oxygen = (2x16) = 32 g
In the formation of SO₃:mass of sulphur = 32 g and mass of oxygen = (3 x 16) = 48 g
Notice, while mass of sulphur is constant, mass of oxygen changed.
The ratio of mass of oxygen in the given two compounds = 32g : 48g = 2:3
Thus, based on the law of multiple proportion, the mass of the oxygen which combined with a fixed mass of the sulphur is in simple whole number ratio of 2 is to 3 (2:3).
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why does copper Cu (I) have a short lifespan
Answer:
Copper (Cu), chemical element, a reddish, extremely ductile metal of Group 11 (Ib) of the periodic table that is an unusually good conductor of electricity and heat. Copper is found in the free metallic state in nature.
Explanation:
hope this helps:)
what is seed reproduction
Answer:
A seed is formed when fertilised ovule divides by mitosis. ... The ovary of the flower develops into the fruit while ovules develop into seeds. The formation of seed completes the process of reproduction in plants. Within the seed, the growing embryo develops and matures.
I hopes it helps you.What kinds of questions cannot be answered by chemistry
What is a mixture? How will you separate the components of a mixture containing sugar, sand and water?
Answer:
Mixture is combination of two or more substances
Explanation:
The sugar would dissolve in water. You could then pour off the solution and wash the remaining sand with a bit more water. Heat the water to evaporate it from the sugar, and the two are separated.
What would most likely happen if the kangaroo rats
were killed off and removed from the food chain?
Answer:
Explanation:
The number of cactus plants would increase.
for the equation given, how many grams of methane will react with a 125g of oxygen
CH4 (g) + 2O2(g) -> CO2(g) +2H2O
Answer:
16
Explanation:
1) in the given equation CH₄+2O₂⇒ 2H₂O+CO₂;
M(CH₄)=12+4=16 (g/mol); M(O₂)=32 (g/mol);
2) if m(O₂)=125 gr., then ν(O₂)=m(O₂)/M(O₂)=125/32≈3.90625 (moles);
3) if in the given equation 'ν' of O₂ is 2, then the 'ν' of CH₄ is 1;
4) m(CH₄)=ν(CH₄)*M(CH₄)=1*16=16 (gr.).
6. Heat from the sun reaches to us by
(a) radiation
(b) conduction
(c) convection
(d) all of these
PS. the one who gets it correct will be followed by me and also be marked as the brainliest!
Answer:
radiation
....
.
.
.
.hi how r u
Is my answer correct
Answer:
Radiation
Explanation:
Heat from the sun reaches is by the process of radiation
3(b) The balloon did not burst when it is pressed onto 100 nails because
1. the nails are not sharp
2.the surface area of 100 nails produce high pressure on the balloon
3. the larger surface area of 100 nails produce low pressure on the balloon
3(c) To reduce pressure on the contact surface, we must apply force onto the .................... surface area.
1.largest
2.smallest
3. Any size of
Which pair of reactants for a Grignard reaction does not give 2-phenylbutan-2-ol after an aqueous workup?
3. If we remember seeing something happen, we can trust that it happened just as we think it did. True or False
[tex] \huge{ \underbrace{ \overbrace{True}}}[/tex]
.
[tex]\huge\mathfrak\purple{Hope \: it \: helps}[/tex]
Note : Because Many of My Dreams came true and I realized.
In nature, Chlorine-35 isotopes (35 amu) make up 75
% of all chlorine. Chlorine-37 (37 amu) isotopes make
up 25 % of all chlorine,
Show your calculation for the AVG. Atomic Mass of
chlorine:
Which method is used to separate the following mixture (a) water + kerosene
Answer:
The separation of kerosene, oil, and water are immiscible liquids, so they can be separated funnel.
Please help thank you (20 points)
Answer:
Answer is b gravity only
identify 2 ways to measure mass
Answer:
The two ways to measure mass are subtraction and taring.
Loss of atmospheric ozone has led to an ozone "hole" over Antarctica. The process occurs in part by three consecutive reactions. (Each of the reactants and products in these reactions are gases.)
(1) Chlorine atoms react with ozone (O3) to form chlorine monoxide and molecular oxygen.
(2) Chlorine monoxide forms ClOOCl.
(3) ClOOCl absorbs sunlight and breaks into chlorine atoms and molecular oxygen. If the coefficient for a particular substance is "1", do not write the "1" in the balanced equation. For example, instead of writing "1Cl(g)", simply write "Cl(g)".
(a) Write a balanced equation for each step, including the state of each molecule.
(b) Write an overall balanced equation for the sequence.
Ozone O₃ consists of a strong reactive gas made up of three atoms of oxygen. Ozone occurs on the Earth as natural and man-made gas.
Ozone impacts life on Earth in positive or harmful ways depending upon its location in the atmosphere.
From the information given, we are to balance the reactant and the product that leads to the formation of Ozone by following each step.
Step 1:
2Cl° + 2O₃ 2ClO° + 2O₂
Chlorine molecular
monooxide oxygen
Step 2:
2ClO° ClOOCl
Step 3:
ClOOCl + sunlight → 2Cl° + O₂
(b)
The Overall balanced equation can be expressed as:
2O₃ → 3O₂
Therefore, from the above explanation we can see the step by step process for the balanced equation and the overall balanced equation.
Learn more about balancing equation here:
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A graduated cylinder is filled with 20ml of water. A rock is dropped in to the graduated cyclinder and the volume of water rises to 30ml
inside the graduated cylinder. The mass of the rock is 23g. What is the density of the rock?
2.3g/ml
0.77g/ml
5g/ml
1.15g/ml
Answer:
[tex]\boxed {\boxed {\sf 2.3 \ g/mL}}[/tex]
Explanation:
We are asked to find the density of a rock. Density is the substance's mass per unit volume. The formula for calculating density is:
[tex]\rho= \frac{m}{v}[/tex]
The mass of the rock is 23 grams. The volume was found using water displacement. A known amount of water was measured, the rock was added to the graduated cylinder, and the water level was recorded again. The volume is the difference between the final and initial water level. The graduated cylinder originally had 20 milliliters and the water rose to 30 milliliters.
volume = final water level - initial water level volume = 30 mL - 20 mLvolume = 10 mLNow we know the mass and the volume.
m= 23 g v= 10 mLSubstitute the values into the formula.
[tex]\rho= \frac{ 23 \ g }{30 \ mL}[/tex]
Divide.
[tex]\rho= 2.3 \ g/mL[/tex]
The density of the rock is 2.3 grams per milliliter.
How many inches are in 4.5 miles?
11) Calcium Chloride, CaCl2, can be used instead of road salt to melt the ice on roads during the winter. To determine how much calcium chloride had been used on a nearby road, a student took a sample of slush to analyze. The sample had a mass of 23.47g. When the solution was evaporated, the residue had a mass of 4.58g (assume that no other solutes were present).
a) What was the mass/mass percent of calcium chloride in the slush
b) How many grams of calcium chloride were present in 100g solution?
Answer:
What is that? I do not understand
