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3 years ago

Technetium-99m, a “metastable” nuclide of

1 answer:

4 0

In beta decay, a neutron is transformed into a proton via emission of an electron. This means that the total nucleon number remains the same; however, the proton number is increased by one (and the neutron number decreases by one). Therefore, the parent atom must also have mass number 99 but be of one less atomic number.
The atomic number of Tc is 43 and proton number 42 is Mo. Therefore, the answer is:
99Mo

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Do the number of atoms change in a chemical reaction?<br> I will give brainliest

padilas [110]

Answer:

No.

Explanation:

The reason comes the <em>Law of Conservation of Mass</em>.

In an ordinary chemical reaction, <em>you cannot create or destroy atoms</em>.

So, you must have as many atoms at the beginning of a reaction (in the reactants) as at the end (in the products)

We use this principle to balance chemical equations.

For example, the equation for the formation of water from hydrogen and oxygen is

2H₂ + O₂ ⟶ 2H₂O

There are four atoms of H and two of O both before and after the reaction.

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3 years ago

True/False: All of the elements combine in a variety of ways to make up all living and all nonliving things

likoan [24]

Answer:

true

Explanation:

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3 years ago

Which properties represent a metal ( select all that apply )

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Malleable, shiny and good conductors
A B E

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3 years ago

Which observation could you make based on stimuli to your photoreceptors?(1 point)

Montano1993 [528]

Answer:

last one which is d

Explanation:

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3 years ago

. In a separate experiment, the molar mass of nicotine is found to be somewhere between 150 and 180 g/mol. Calculate the molar m

stealth61 [152]

Answer:

Explanation:

The question is incomplete. The complete question includes the information to find the empirical formula of nicotine:

<em>Nicotine has the formula </em> $C_xH_yN_z$ <em> . To determine its composition, a sample is burned in excess oxygen, producing the following results:</em>

<em>1.0 mol of CO₂</em>

<em>0.70 mol of H₂O</em>

<em>0.20 mol of NO₂</em>

<em>Assume that all the atoms in nicotine are present as products </em>

<h2>Solution</h2>

To find the empirical formula you need to find the moles of C, H, and N in each of the compound.

1.0 mol of CO₂ has 1.0 mol of C

0.70 mol of H₂O has 1.4 mol of H

0.20 mol of NO₂ has 0.20 mol of N

Thus, the ratio of moles is:

C: 1.0

H: 1.4

N: 0.20

Divide all by the smallest number: 0.20

C: 1.0 / 0.20 = 5

H: 1.4 / 0.20 = 7

N: 0.20 / 0.20 = 1

Hence, the empirical formula is C₅H₇N

Find the mass of 1 mole of units of the empirical formula:

C: 5mol × 12g/mol = 60g

H: 7mol × 1g/mol = 7 g

N: 1 mol × 14g/mol = 14g

Total mass = 60g + 7g + 14g = 81g

Two moles of units of the empirical formula weighs 2 × 81g = 162g and three units weighs 3 × 81g = 243 g.

Thus, since the molar mass is between 150 and 180 g/mol, the correct molar mass is 162g/mol and the molecular formula is twice the empirical formula: C₁₀H₁₄N₂.

5 0

3 years ago