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ICE Princess25 [194]
2 years ago
9

An atom has 18 protons and 8 valence electrons which statement would best identify this element

Chemistry
2 answers:
lorasvet [3.4K]2 years ago
7 0
Argon has 18 protons which identifies the element and is in group Noble Gases which has 8 valence electrons.
fgiga [73]2 years ago
3 0
It would argon because the atomic number is the same as the protons.
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The transition metal with the smallest atomic mass
solniwko [45]
The transition metal with the smallest atomic mass is Scandium (Sc).
Hope this helps~
8 0
2 years ago
Water treatment plants commonly use chlorination to destroy bacteria. a byproduct is chloroform (chcl3), a suspected carcinogen
antiseptic1488 [7]
<span>100. ppb of chcl3 in drinking water means  100 g of CHCl3 in 1,000,0000,000 g of water

Molarity, M

M = number of moles of solute / volume of solution in liters

number of moles of solute = mass of CHCl3 / molar mass of CHCl3

molar mass of CHCl3 = 119.37 g/mol

number of moles of solute = 100 g / 119.37 g/mol = 0.838 mol

using density of water = 1 g/ ml => 1,000,000,000 g = 1,000,000 liters

M = 0.838 / 1,000,000 = 8.38 * 10^ - 7 M <----- answer

Molality, m

m = number of moles of solute / kg of solvent

number of moles of solute = 0.838

kg of solvent = kg of water = 1,000,000 kg

m = 0.838 moles / 1,000,000 kg = 8.38 * 10^ - 7 m <----- answer

mole fraction of solute, X solute

X solute = number of moles of solute / number of moles of solution

number of moles of solute = 0.838

number of moles of solution = number of moles of solute + number of moles of solvent

number of moles of solvent = mass of water / molar mass of water = 1,000,000,000 g / 18.01528 g/mol = 55,508,435 moles

number of moles of solution = 0.838 moles + 55,508,435 moles = 55,508,436 moles

X solute = 0.838 / 55,508,435 = 1.51 * 10 ^ - 8 <------ answer

mass percent, %

% = (mass of solute / mass of solution) * 100 = (100g / 1,000,000,100 g) * 100 =

% = 10 ^ - 6 % <------- answer
</span>
7 0
2 years ago
Read 2 more answers
A converging lens with a focal length of 70.0cm forms an image of a 3.20-cm-tall real object that is to the left of the lens. Th
Setler [38]

Answer: (i)The object is at a distance of 120cm from the lens while the image is at a distance of 160cm from the lens. (ii)The image is Real

Note: This is the complete question; A converging lens with a focal length of 70.0cm forms an image of a 3.20-cm-tall real object that is to the left of the lens. The image is 4.50cm tall and inverted. Where are the object and image located in relation to the lens? Is the image real or virtual?

Explanation:

The required formulas are;

1. lens formula given by,  <em>1/s' + 1/s = 1/f</em>

2. magnification = <em>h'/h = s'/s</em>

where h' is image height, h is object height, s' is image distance, s is object distance, f is focal length of lens.

h' = 4.50cm, h = 3.20cm, f = 70cm ( f of a converging lens is positive)

solving for s' and s in eqn (2)

4.50/3.20=s'/s

1.4=s'/s

s'=1.4s

to find the values of s' and s, we use equation (1) and substitute s' = 1.4s

1/1.4s + 1/s = 1/70

2.4/1.4s =1/70

s = 2.4*70/1.4 = 120cm

s' = 1.4*120 = 160cm

Therefore, the object is on the left, 120cm from the lens while the image is 160cm on the right of the lens

<em>Since the object is at a distance between f and 2f from the lens, the image formed is</em> real, inverted and magnified

3 0
2 years ago
Which conjugate pair is suited best to make this buffer? Which conjugate pair is suited best to make this buffer? Phosphoric aci
Juliette [100K]

Answer:

bkfhjjfrsxtr

Explanation:

4 0
2 years ago
Calculate δg o for each reaction using δg of values:(a) h2(g) + i2(s) → 2hi(g) kj (b) mno2(s) + 2co(g) → mn(s) + 2co2(g) kj (c)
steposvetlana [31]
Part (a) :
H₂(g) + I₂(s) → 2 HI(g)
From given table:
G HI = + 1.3 kJ/mol
G H₂ = 0
G I₂ = 0
ΔG = G(products) - G(reactants) = 2 (1.3) = 2.6 kJ/mol

Part (b):
MnO₂(s) + 2 CO(g) → Mn(s) + 2 CO₂(g)
G MnO₂ = - 465.2
G CO = -137.16
G CO₂ = - 394.39
G Mn = 0
ΔG = G(products) - G(reactants) = (1(0) + 2*-394.39) - (-465.2 + 2*-137.16) = - 49.3 kJ/mol

Part (c):
NH₄Cl(s) → NH₃(g) + HCl(g)
ΔG = ΔH - T ΔS
ΔG = (H(products) - H(reactants)) - 298 * (S(products) - S(reactants))
      = (-92.31 - 45.94) - (-314.4) - (298 k) * (192.3 + 186.8 - 94.6) J/K
      = 176.15 kJ - 84.78 kJ = 91.38 kJ 
 





 
6 0
2 years ago
Read 2 more answers
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