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klemol [59]
3 years ago
7

1. Which of the following best describes natural selection?

Chemistry
1 answer:
Shalnov [3]3 years ago
8 0

Answer:

D

Explanation:

according to Darwin, out of the vast no of individuals which compete for a place in the world, only those having advantageous variations survive and reproduce

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The rate of a certain reaction is given by the following rate law: rate Use this information to answer the question below. At a
AleksAgata [21]

Answer:

Initial rate of the reaction when concentration of hydrogen gas is doubled will be 3.2\times 10^6 M/s.

Explanation:

N_2+3H_2\rightarrow 2NH_3

Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

Initial rate of the reaction = R = 4.0\times 10^5 M/s

R = k\times [N_2][H_2]^3

4.0\times 10^5 M/s=k\times [N_2][H_2]^3

The initial rate of the reaction when concentration of hydrogen gas is doubled : R'

[H_2]'=2[H_2]

R'=k\times [N_2][H_2]'^3=k\times [N_2][2H_2]^3

R'=8\times k\times [N_2][H_2]^3

R'=8\times R=8\times 4\times 10^5 M/s=3.2\times 10^6 M/s

Initial rate of the reaction when concentration of hydrogen gas is doubled will be 3.2\times 10^6 M/s.

7 0
3 years ago
15
Vinil7 [7]

Answer:

barium and silicon has same valence electrons

Explanation:

barium-2,8,18,18,8,2

neon-2,8

silicon-2,8,2,2

carbon-2,4

5 0
3 years ago
What is the molecular structure of water? What are the physical and chemical properties of water?
Slav-nsk [51]
Water (H
2O) is a polar inorganic compound that is at room temperature a tasteless and odorless liquid, which is nearly colorless apart from an inherent hint of blue. It is by far the most studied chemical compound and is described as the "universal solvent" [18][19] and the "solvent of life".[20] It is the most abundant substance on Earth[21] and the only common substance to exist as a solid, liquid, and gas on Earth's surface.[22] It is also the third most abundant molecule in the universe.[21]

Water (H
2O)





NamesIUPAC name

water, oxidane

Other names

Hydrogen hydroxide (HH or HOH), hydrogen oxide, dihydrogen monoxide (DHMO) (systematic name[1]), hydrogen monoxide, dihydrogen oxide, hydric acid, hydrohydroxic acid, hydroxic acid, hydrol,[2] μ-oxido dihydrogen

Identifiers

CAS Number

7732-18-5 

3D model (JSmol)

Interactive image

Beilstein Reference

3587155ChEBI

CHEBI:15377 

ChEMBL

ChEMBL1098659 

ChemSpider

937 

Gmelin Reference

117

PubChem CID

962

RTECS numberZC0110000UNII

059QF0KO0R 

InChI

InChI=1S/H2O/h1H2 

Key: XLYOFNOQVPJJNP-UHFFFAOYSA-N 

SMILES

O

Properties

Chemical formula

H
2OMolar mass18.01528(33) g/molAppearanceWhite crystalline solid, almost colorless liquid with a hint of blue, colorless gas[3]OdorNoneDensityLiquid:[4]
0.9998396 g/mL at 0 °C
0.9970474 g/mL at 25 °C
0.961893 g/mL at 95 °C
Solid:[5]
0.9167 g/ml at 0 °CMelting point0.00 °C (32.00 °F; 273.15 K) [a]Boiling point99.98 °C (211.96 °F; 373.13 K) [6][a]SolubilityPoorly soluble in haloalkanes, aliphaticand aromatic hydrocarbons, ethers.[7]Improved solubility in carboxylates, alcohols, ketones, amines. Miscible with methanol, ethanol, propanol, isopropanol, acetone, glycerol, 1,4-dioxane, tetrahydrofuran, sulfolane, acetaldehyde, dimethylformamide, dimethoxyethane, dimethyl sulfoxide, acetonitrile. Partially miscible with Diethyl ether, Methyl Ethyl Ketone, Dichloromethane, Ethyl Acetate, Bromine.Vapor pressure3.1690 kilopascals or 0.031276 atm[8]Acidity (pKa)13.995[9][10][b]Basicity (pKb)13.995Conjugate acidHydroniumConjugate baseHydroxideThermal conductivity0.6065 W/(m·K)[13]

Refractive index (nD)

1.3330 (20 °C)[14]Viscosity0.890 cP[15]Structure

Crystal structure

Hexagonal

Point group

C2v

Molecular shape

Bent

Dipole moment

1.8546 D[16]Thermochemistry

Heat capacity (C)

75.375 ± 0.05 J/(mol·K)[17]

Std molar
entropy (So298)

69.95 ± 0.03 J/(mol·K)[17]

Std enthalpy of
formation (ΔfHo298)

−285.83 ± 0.04 kJ/mol[7][17]

Gibbs free energy (ΔfG˚)

−237.24 kJ/mol[7]
6 0
3 years ago
A heterogeneous mixture is a :
4vir4ik [10]
The correct answer is letter <span>C. mixture in which its components retain their identity. A heterogeneous mixture is a mixtures in which the component of the mixed are not uniform. You can see that there are localized regions that have different properties. The components have the capacity to retain their identity.</span>
8 0
3 years ago
Read 2 more answers
What happens to the density of group 1 when you go down the group
OLga [1]

the density increases down the group.

4 0
2 years ago
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