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Vika [28.1K]
2 years ago
13

Pick the correct statement for the following isotope: a. 42Ca 42 is the mass number and 20 is the atomic number. b. 42 is the nu

mber of neutrons and 20 is the number of protons. c. 42 is the number of protons and 20 is the number of electrons. d. 42 is the atomic number and 20 is the number of neutrons.
Chemistry
1 answer:
kramer2 years ago
4 0

Answer:

A

Explanation:

To label an element correctly using a combination of the symbol, mass number and atomic number furnishes some important information about the element.

We can obtain these information from the element provided that correct labeling of the element is presented. Firstly, after writing the symbol of the element, the atomic number is placed as a subscript on the left while the mass number of the atomic mass is placed as a superscript on the same left.

Looking at the question asked, we have the element symbol in the correct position as Ca, with 42 also in the correct position which is the mass number. The third number which is 20 is thus the atomic number of the element.

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hram777 [196]
The correct answer is:  [C]:  "polar" .
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   " Water " ; which is:  " H₂O " ; 
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is a:
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  — polar;  → {eliminate:  "Choice  [A]:  "non-polar"} ;

                  → {and consider:  "Choice: [C]:  "polar" } ; 

  — covalent; → {not "ionic";  eliminate:  "Choice:  [B]:  "ionic"} ;

  — uncharged;  → {neutral compound; not "charged" —but "balanced"} ; 
 
                           →  {Note:   " H ⁺ ,  O ²⁻  ;   →   " H₂O " } ;

                           →  The "charges" balance/ cancel out. 

                           →  {eliminate:  "Choice:  [D]:  "charged" .}.
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    — 
compound.
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The correct answer is:  [C]:
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6 0
3 years ago
Three samples of wood with the same volume were weighed. Sample A has a mass of 224.96 g, sample B has a mass of 0.55632 Ibs, an
sertanlavr [38]

Answer:

sample C have the highest density

Explanation:

Data Given:

mass of sample A = 224.96 g

Convert g to kg

1 g = 0.001 Kg

224.96 g = 224.96 x 0.001 = 0.225 kg

mass of sample B = 0.55632 Ibs

Convert lbs to kg

2.21 lb = 1 kg

0.55632 Ibs = 0.55632 / 2 = 0.278 kg

mass of sample C = 0.30648 kg

Solution:

To calculate density of every sample we have the following formula

            d = m/v . . . . . . . . . . (1)

It is clear from the formula that density have direct relation with mass and inverse relation with volume, that is density increase with increasing in mass.

As we have same volume of wood sample, so suppose that each sample have volume of  2 cm³

So now we find density for each sample

As for sample A

  • mass of sample A = 0.225 kg
  • supposed volume = 2 cm³

Put values in formula 1

                d = 0.225 kg / 2 cm³

                d = 0.128 kg/cm³

As for sample B

  • mass of sample A = 0.278 kg
  • supposed volume = 2 cm³

Put values in formula 1

                d = 0.278 kg / 2 cm³

                d = 0.139 kg/cm³

As for sample C

  • mass of sample C = 0.30648 kg
  • supposed volume = 2 cm³

Put values in formula 1

                d = 0.30648 kg / 2 cm³

                d = 0.153 kg/cm³

So it shows that sample C have the highest density that is 0.153 kg/cm³ . As it have the highest mass too among all samples.

5 0
2 years ago
Which of the following causes tornadoes
Shkiper50 [21]

Cool dry air meeting warm Moist air

7 0
3 years ago
Read 2 more answers
Which objects could you stand near to feel the heat​
4vir4ik [10]

Answer:

An heater, Oven, sun, and fireplaces

Chose which ever you want

4 0
3 years ago
Silicon carbide, SiC, is commonly known as carborundum. This hard substance, which is used commercially as an abrasive, is made
mrs_skeptik [129]

Mass of SiC = 2 g

<h3>Further explanation</h3>

Given

Reaction

SiO₂(s) + 3C(s) → SiC(s) + 2CO(g)

3.00 g of SiO₂

4.50 g of C

Required

mass of SiC

Solution

mol SiO₂ (MW=60,08 g/mol) :

= 3 g : 60.08 g/mol

= 0.0499

mol C(Ar = 12 g/mol) :

= 4.5 g : 12 g/mol

= 0.375

mol : coefficient of reactants =

SiO₂ : 0.0499/1 = 0.0499

C : 0.375/3 = 0.125

SiO₂ as a limiting reactant(smaller ratio)

Mol SiC based on mol SiO₂ = 0.0499

Mass SiC :

= mol x MW

= 0.0499 x 40,11 g/mol

= 2 g

3 0
2 years ago
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