PLEASE HURRY!
What is the half-life of a 12 g sample of radioisotope that decayed to 6 g in 28
years?
A. 14 years
B. 7 years
C. 56 years
D. 28 years
Answer:
28 years
Explanation:
the information is literally in the question.
Explain a polar molecules and give examples
bf3 can be octet or not
Answer:
(BH3 follows the octet rule by dimerizing, as Hadi Kurniawan AR pointed out.) For H and He, an "octet" = 2 electrons. Boron does prefer to follow the octet rule, in that it likes to form borate compounds such as NaBH4. It also is happy to form compounds with elements with lone pairs.
Nitrogen is a group 15 element. What does being In this group imply about the structure of the nitrogen atom?
Answer:
Nitrogen has 5 valence electrons
Explanation:
nitrogen has it's attoms form triple bonds which are very hard to break
so non-reactive
Pleaseee helpppp.....
Answer:
C. All of the above
Explanation:
They all happen beyond critical point.
Which value could be the y-coordinate for point Q?
215
42
2/13
8/2
Which three types of reactions yield a product that is a chemically bonded combination of reactants?
Answer:
oxidation, synthesis, polymerization.
4. If the relative molecular mass of CH20 is 60.
calculate its empirical formula. (C = 12. H = 1
0 = 16)
A 4
В І
C2
D 3
Answer:
C2H4O2
Explanation:
because you do mr of CH2O= 12+2+16=30
so 60÷30=2 empirical units
so CH2O × 2=C2H4O2
hope this helps :)
The Empirical formula of the given compound is CH₂O
What is Empirical formula ?A formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms.
Empirical formula mass = 12g/mol + 2 g/mol + 16 g/mol = 30 g/mol
Molecular formula mass / Empirical formula mass = 60 g/mol / 30 g/mol
= 2
Molecular formula = 2 × CH₂O = C₂H₄O₂
Empirical formula = CH₂O
Empirical formula mass = 12g/mol + 2 g/mol + 16 g/mol = 30 g/mol
Therefore, The Empirical formula of the given compound is CH₂O
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What will change if liquid 5.0 molar NiCl2 is added?
When liquid 5.0 molar NiCl₂ is added to 0.3 M of NiCl₂ solution :
Molarity will increase ( A )
What is Molarity ?
Molarity is the measure of the number of moles of solute present per volume of the solution. The addition of 5.0 molar nickel chloride into a 0.3M Nickel chloride solution will lead to an increase in the number of moles of Nickel chloride present in the solution.
Molarity is directly proportional to moles of solute in a solution therefore the molarity of the solution will increase.
Hence we can conclude that When liquid 5.0 molar NiCl₂ is added to 0.3 M of NiCl₂ solution : Molarity will increase.
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ASAP!!!!!!!!!!!!A marble bag contains 10 red marbles, 19 yellow marbles, and 29 green marbles. What is the % composition of each color marble in the bag?
Answer:
Red: 17.24%
Yellow: 32.76%
Green: 50%
Explanation:
PLEASE HELP ME!
When magnesium powder is heated, it combines with oxygen to form white magnesium oxide powder.
(a) State one use of magnesium oxide.
(b) Write the chemical equation of this reaction.
(c) Calculate the mass of magnesium oxide formed if 3g magnesium is completely burnt in excess oxygen.
(d) The magnesium oxide is basic and reacts with hydrochloric acid to form magnesium chloride salt and water. Write the chemical equation of this reaction. (Relative atomic mass of O=16,Mg=24)
Explanation:
a. Magnesium oxide is used mainly in soil treatment and groundwater remediation, wastewater treatment, etc. it is used for it's acid buffering capacity and effectiveness in dissolving heavy metals.
b. MgO is the chemical equation for the reaction.
c. multiply the given mass of O2 by the inverse of it's molar mass. multiply the molar ratio (from the balanced equation) between O2 and MgO. Multiply by the molar mass of MgO. 32g O2 x 1 mol O2 ... 32g O2 x 2mol MgO 1mol O2 x 40g MgO. .... 1mol MgO = 80 g.
d. Mg (s) + 2 HCl (aq) produces MgCl 2(aq) + H 2 (g). Where the letter "s" stands for solids, and "g" is for gas and "aq" represents aqueous solution.
Which substance would require the most energy to heat 10.00 g of it by 10.0°C?
O Ice, c = 2.03 Jigº
O Mercury, c = 0.140 J/gºC
O Water, c = 4.18 J/gºC
O Aluminum, c = 0.902 J/gºC
Answer:
a
Explanation:
a
Which is true of the enthalpy of a reaction?
A. Its value depends on which reactions are added
B. Its value is the same as the enthalpy of each intermediate reaction
c. Its value is always a negative kJ/mol
D. Its value does not depend on which reactions are added
D. It’s value does not depend on which reactions are added
7) The negative-feedback system of the endocrine system works much like a ______
Answer: Most of the hormones released by endocrine system are regulated by negative feedback mechanism.
- Negative feedback mechanism functions to reduce the intensity of original stimulus in order to maintain homeostasis.
Explanation:
When blood calcium levels are decreased, parathyroid gland releases parathyroid hormone (PTH).
PTH acts on bone and stimulate bone resorption by promoting osteoclastic activity. It stimulates reabsorption of calcium in kidneys. PTH promotes calcitriol synthesis that acts on small intestine to increase calcium absorption.
Action of PTH increases blood calcium levels.
When blood calcium levels are increased, thyroid gland releases hormone calcitonin.
Calcitonin opposes PTH and acts to deposit calcium in the bone.
Calcitonin acts on osteoblasts and promote increase in bone mass.
Action of calcitonin decreases blood calcium levels.
The correct pathway for air entering the human respiratory system is _______.
A)nose, trachea, alveoli, bronchi
B)nose, bronchi, trachea, alveoli
C)alveoli, trachea, epiglottis, nose
D)nose, trachea, bronchi, alveoli
Answer: D
Explanation:
The closest living relatives to Gorillas are:
(Look at pic)
A. Humans
B. Chimpanzees, and humans equally
C. Orangutans
D. Chimpanzees
(DO NOT ANSWER IF YOU CANNOT ACTUALLY HELP)
Which of the following is the correct electron
configuration for titanium (Ti)?
Answer:
1s2 2s2 2p6 3s2 3p6 4s2 3d2
Explanation:
1s2 2s2 2p6 3s2 3p6 4s2 3d2
Which statement best supported by the data on the map
Q1.what is irragation
Answer:
Irrigation is the artificial process of applying controlled amounts of water to land to assist in production of crops. Irrigation helps to grow agricultural crops, maintain landscapes, and revegetate disturbed soils in dry areas and during periods of less than average rainfall.
Answer: The watering of crop plants in regular intervals is known as irrigation. ... Weeds are unwanted plants thet grows with the crop plants. Weeding means to remove those plants. It is done manually or by machine. Using khurpi it is done manually and using seed drill it is done by machine.
Explanation:
Irrigation is the artificial application of water to the soil through various systems of tubes, pumps, and sprays. Irrigation is usually used in areas where rainfall is irregular or dry times or drought is expected.
Hope it helps
already answered but i would appreciate it if someone checked for me !!
Answer:
correct
Explanation:
I belve ou got it
Which of the following elements is a metalloid (semimetal)?
C
P
Sb
N
In
Answer:
Sb
Explanation:
Sb (antimony) is an metalloid
magnesium hydroxide + sulfuric acid please
Answer:
H2SO4 + Mg(OH)2 → H2O + MgSO4
Explanation:
when magnesium hydroxide reacts with sulfuric acid you get magnesium sulfate
hope this helps
Help I dont know how to do this
Which of the following issues surrounding nuclear power creates the biggest
concern?
A. Where nuclear power should be used
B. How to deal with the radioactive waste
c. How many power plants should be built
O D. What nuclear power should be used for
Question : Which issue surrounding nuclear power creates the biggest concern?
Answer : How to deal with the radioactive waste (B)
The following issues surrounding nuclear power that create the biggest concern is What nuclear power should be used for?
What is nuclear power?Nuclear powers are those powers that are produced by nuclear reactions. These reactions include nuclear fission, nuclear fusion, and nuclear decay. Nuclear power is currently in use to produce electricity. The reaction uses uranium and plutonium reaction to produce electricity.
Nuclear power is used for generating electricity, and it is necessary to use the correct radioisotopes to produce electricity.
Thus, the correct option is D. What nuclear power should be used for?
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This cell is dividing into two cells.
Answer:
answer: B or D
Explanation:
hope it helps thanks❤
What is the amount of heat, in joules, required to increase the temperature of a 49.5-gram sample of water from 22°C to 66°C?
1) 2.2 x 103^3 J
2) 4.6 10^3 J
3) 9.1 x 10^3 J
4) 1.4 x 10^4 J
Answer:
3) 9.1 x 10^3 J
Explanation:
Đốt cháy hoàn toàn 0,1 mol axit đơn chức cần V lít O2 ở đktc. Thu được 0,3 mol CO2 và 0,2 mol h20 vậy giá trị V là
Answer:
Complete combustion of 0.1mol of monocarboxylic acid requires V litres of O2 at dtc. and the reaction produces 0.3mol of CO2 and 0.2mol of H2O.
What is the value of V?
Explanation:
The balanced chemical equation of the reaction is
[tex]HCOOH+O_2 -> 2CO_2+2H_2O\\[/tex]
1mol. of acid reacts with 1mol of [tex]O_2[/tex] and produce 2mol. of CO2 and 2mol. of H2O.
Given,
0.1mol of acid requires how many litres of oxygen at STP?
0.1mol of acid requires 0.1mol of oxygen.
Since, 1mol of oxygen at STP occupies 22.4L of volume.
Hence, the volume occupied by 0.1mol of oxygen is -- 2.24L
Answer is:
The value of V is 2.24L.
The emission spectrum of hydrogen is shown below. What do the lines in the
spectrum show?
A. Light with wavelengths between 410 nm to 434 nm, 434 to 486 nm, and 486 to 656 nm corresponds with the three energy levels in
hydrogen
B. Only light with wavelengths of 410 nm, 434 nm, 486 nm, and 656 nm is not taken in during energy transitions.
C. Light with wavelengths of 410 nm, 434 nm, 486 nm, and 656 no corresponds with the four energy levels in hydrogen.
D. Light with wavelengths of 410 nm, 434 nm, 486 nm, and 656 nm is given off when electrons fall to lower energy levels.
Answer:
A
Explanation:
Same air has special carakteristik features
Which number is equal to the number of protons in the atom
Answer:
The number of electrons is equal to the number of protons
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, the electrons number is equal to the number of protons in the atom.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron. In an atom, the number of electron or atomic number is s equal to the number of protons in the atom.
Therefore, the electrons number is equal to the number of protons in the atom.
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When 11.2 liters of hydrogen gas is made by adding zinc to sulfuric acid, what mass
of zinc is needed?
Zn + H2SO4 -> H2 + ZnSO4
32.7 g Zn
Explanation:
First convert the amount of gas into moles:
11.2 L H2 × (1 mol H2/22.4 L H2) = 0.500 mol H2
Then use the molar ratio to find the amount of zinc necessary to produce the amount of gas above:
0.500 mol H2 × (1 mol Zn/1 mol H2)
= 0.500 mol Zn
Now use the molar mass of zinc to find the number of grams of zinc for the reaction to occur:
0.500 mol Zn × (65.38 g Zn/1 mol Zn)
= 32.7 g Zn
