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tino4ka555 [31]
3 years ago
8

Which of these substances are elements?

Chemistry
2 answers:
Aleks04 [339]3 years ago
8 0
An element is a species of atom that has the same amounts of electrons and protons in their nuclei. To know which of these substances are elements, we can look it up in the periodic table of elements. The elements are as follows:

1.silicon
2.lead
3.silicone
5.iodine

Andru [333]3 years ago
8 0

Answer is:

1. silicon.

2. lead.

5. iodine.

Silicon (symbol: Si) is an element with atomic number 14 (14 protons).

Lead (Pb) is an element with atomic number 82.

Iodine (I) is an element with atomic number 53.

Silicone is a compound (polymer) made of silicon, oxygen, hydrogen, carbon and other elements.

Quartz is a compound (mineral) made of silicon and oxygen atoms.

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Why is hydrogen placed in group one of the<br> periodic table?
Mice21 [21]

Answer:

Hydrogen has only 1 valence electron in its outermost shell.

Explanation:

6 0
4 years ago
Determine the equilibrium pH and speciation (concentration of each species) of the following two solutions. Neglect activity cor
irina [24]

Answer:

HCl solution - H30+ and Cl ions. pH 3

NaCl - Na+ and Cl-. pH 7

Explanation:

a) HCl solution - the hydrogen ion combines with water molecule to form the hydronium molecule which is responsible for acidity. The chloride ion is also found in solution.

pH = -log [H+] = -log(10^-3) = 3

b) NaCl 10-3 g. The solid dissocates in water forming the Na+ and Cl- ions. None of these ions affect pH

5 0
4 years ago
Consider the combustion reaction for octane (C8H18), which is a primary component of gasoline.
lesya692 [45]

Answer:

n_{CO_2}=1.93 gCO_2

Explanation:

Hello,

In this case, considering the given chemical reaction, we can use the molar mass of octane (114.23 g/mol) and the 2:16 molar ratio with carbon dioxide to compute the emitted moles of CO2 to the atmosphere via the following stoichiometric procedure:

n_{CO2}=27.6gC_8H_{18}*\frac{1molC_8H_{18}}{114.23gC_8H_{18}}  *\frac{16molCO_2}{2molC_8H_{18}} \\\\n_{CO_2}=1.93 gCO_2

Which also corresponds to the following mass:

m_{CO_2}=1.93molCO_2*\frac{44gCO_2}{1molCO_2} \\\\m_{CO_2}=85.0gCO_2

Best regards.

6 0
3 years ago
Calculate the hydrogen-ion concentration [H+] for the aqueous solution in which [OH-] is 1 x 10-2 mol/L. Is this solution acidid
Lilit [14]

Answer:

[H⁺] = 1.0 x 10⁻¹² M.

Explanation:

<em>∵ [H⁺][OH⁻] = 10⁻¹⁴. </em>

[OH⁻] = 1 x 10⁻² mol/L.

∴ [H⁺] =  10⁻¹⁴/[OH⁻] = (10⁻¹⁴)/(1 x 10⁻² mol/L) = 1.0 x 10⁻¹² M.

∵ pH = - log[H⁺] = - log(1.0 x 10⁻¹² M) = 12.0.

∴ The solution is basic, since pH id higher than 7 and also the  [OH⁻] > [H⁺].

6 0
4 years ago
Which of these remains unchanged during the compaction of sediments? A) Mass B) Color C) Volume D) Pore Space
AURORKA [14]
Mass! Remember the Law of Conservation of Mass: mass can neither be created nor destroyed.
8 0
3 years ago
Read 2 more answers
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