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3 years ago

Which of the following statements is true about the periodic table.

Chemistry

2 answers:

mixer [17]3 years ago

8 0

Answer:

In this question, the statement 2 is correct and true while other statements are incorrect.

Explanation:

The properties of an element can be easily predicted from the periodic table. We can find out the atomic number of the element from the periodic table. According to the periodic table, the properties of element is dependent on the atomic number of the element. The behavior of element during a chemical reaction can be predicted from the atomic number.

Element can only belong to one group at a time. Hence, statement (3) is not correct.

The periodic table is still used by scientists for predicting the properties. Hence, it is not outdated. Statement (1) is not correct.

Statement (2) is correct

kodGreya [7K]3 years ago

5 0

Answer: 2

Explanation:

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3 years ago

1.20 x 10^22 molecules NaOH to gram

Trava [24]

Answer:

$\boxed {\boxed {\sf 0.797 \ g \ NaOH}}$

Explanation:

1. Convert Molecules to Moles

First, we must convert molecules to moles using Avogadro's Number: 6.022*10²³. This tells us the number of particles in 1 mole of a substance. In this case, the particles are molecules of sodium hydroxide.

$\frac {6.022*10^{23} \ molecules \ NaOH} {1 \ mol \ NaOH}}$

Multiply by the given number of molecules.

$1.20*10^{22} \ molecules \ NaOH *\frac {6.022*10^{23} \ molecules \ NaOH} {1 \ mol \ NaOH}}$

Flip the fraction so the molecules cancel out.

$1.20*10^{22} \ molecules \ NaOH *\frac {1 \ mol \ NaOH} {6.022*10^{23} \ molecules \ NaOH}}$

$1.20*10^{22} *\frac {1 \ mol \ NaOH} {6.022*10^{23}}}$

$\frac {1.20*10^{22} \ mol \ NaOH} {6.022*10^{23}}}$

$0.0199269345732 \ mol \ NaOH$

2. Convert Moles to Grams

Next, we convert moles to grams using the molar mass.

We must calculate the molar mass using the values on the Periodic Table. Look up each individual element.

Na: 22.9897693 g/mol
O: 15.999 g/mol
H: 1.008 g/mol

Since the formula has no subscripts, we can simply add the molar masses.

NaOH: 22.9897693+15.999+1.008=39.9967693 g/mol

Use this as a ratio.

$\frac {39.9967693 \ g \ NaOH }{1 \ mol \ NaOH}$

Multiply by the number of moles we calculated.

$0.0199269345732 \ mol \ NaOH*\frac {39.9967693 \ g \ NaOH }{1 \ mol \ NaOH}$

The moles of sodium hydroxide cancel.

$0.0199269345732 *\frac {39.9967693 \ g \ NaOH }{1}$

$0.0199269345732 *39.9967693 \ g \ NaOH$

$0.79701300498 \ g \ NaOH$

The original measurement of molecules has 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place. The 0 tells us to leave the 7 in the hundredth place.

$0.797 \ g \ NaOH$

1.20*10²² molecules of sodium hydroxide is approximately 0.797 grams.

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2 years ago

Which is the most active nonmetallic element in group 16?

timama [110]

Oxygen

For metals, reactivity increases as we move through the elements in the period table from top to bottom, and left to right. In contrast, for nonmetals, reactivity increases as we move through the elements in the periodic table, as we move from bottom to the top, and right to left.

Group 16 on the periodic table is also called the oxygen family or chalcogens. It includes the following elements from top to bottom: Oxygen, Sulfur, Selenium, Tellurium, and Polonium. Of these, only Oxygen, Sulfur, and Selenium are nonmetals. Since reactivity of nonmetals increases going up the periodic table, oxygen is therefore the most reactive nonmetal in the group. Shown in the figure below is the reactivity trend in the periodic table.

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