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MrRa [10]
3 years ago
15

A radioactive nuclide that is used for geological dating has an atomic number of 19 and mass number 40. Which is the symbol of t

his nuclide?

Chemistry
2 answers:
Alina [70]3 years ago
7 0
The mass number goes on top, and the atomic number goes on bottom. 
Therefore, the answer is C:
40
     K
19

aleksklad [387]3 years ago
3 0

Answer:

C. 40/19 K

Explanation:

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How many molecules are in 6.0g of sodium phosphate?
Phantasy [73]

Answer:

2.2 x 10²² molecules.

Explanation:

  • Firstly, we need to calculate the no. of moles in (6.0 g) sodium phosphate:

<em>no. of moles = mass/molar mass </em>= (6.0 g)/(163.94 g/mol) = <em>0.0366 mol.</em>

  • <em>It is known that every mole of a molecule contains Avogadro's number (6.022 x 10²³) of molecules.</em>

<em />

<u><em>using cross multiplication:</em></u>

1.0 mole of sodium phosphate contains → 6.022 x 10²³ molecules.

0.0366 mole of sodium phosphate contains → ??? molecules.

<em>∴ The no. of molecules in  6.0 g of sodium phosphate</em> = (6.022 x 10²³ molecules)(0.0366 mole)/(1.0 mole) = <em>2.2 x 10²² molecules.</em>

3 0
3 years ago
An air mass usually forms in an area of _____. low pressure because it's stable low pressure because it's unstable high pressure
horsena [70]

Answer: high pressure because it's stable

Explanation:

Air mass is volume of air which has stable temperature, humidity and pressure horizontally. Over time, each air mass acquires properties of the region by residing over same part of a surface.

Areas of low pressure and high pressure occur where there is warm air and cold air respectively. An air mass usually forms over an area of high pressure. Warm air rises up and cold air takes its place. Warm air has low density and low pressure where as cold air has high density and pressure and therefore, sinks to the bottom. This is a stable condition.  The movement of air mass is responsible for maintenance of temperature conditions on Earth.

6 0
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Which of the following statements related to S N1 reactions is not true? - The heterolysis of a bond between atoms which do not
Varvara68 [4.7K]

Answer:

The charged carbon atom of a carbocation has a complete octet of valence shell electrons

Explanation:

A charged carbon atom of a carbocation has a valence shell that is not filled, <u>that's why it acts as an electrophile (or a Lewis base)</u>. This unfilled valence shell is also the reason of the nucleophilic attack that takes place during the second step of a SN1 reaction.

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2 Mg + 1 O2 = 2 MgO.
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Anettt [7]
The correct answer here is C. Dew forms on the grass.

Water is a polar substance, which means it has many unique properties. One of which, is its ability to adhere and cohere to surfaces and substances. This particular question is asking about the cohesive properties of water, meaning it’s ability to stick to itself (through bonding.) The only answer choice that represents a situation where water is linking up with other molecules of water are dew drops. The water comes together using cohesion to form the drop and hen the water’s high surface tension properties meet the dew drop’s shape. The other answer choices describe alternate processes like: freezing, melting, and evaporation, respectively.

I hope this helps! :)
4 0
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