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3 years ago

An atom has 5 neutrons,2electrons and 4 protons what type of atom is it

Chemistry

1 answer:

satela [25.4K]3 years ago

8 0

Answer:

Cation

Explanation:

Since the protons are greater than electrons, this means the atom has a net positive charge on it and is now called a cation.

As there are 4 protons, this means that the outermost shell has 2 valence electrons 2s1, 2s2 and this is Group 2 element. Looking at Periodic table, we find that this is beryllium 4Be5 and is denoted as Be^2+

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What should scentist use after completing a scientific investigation

Zinaida [17]

Answer:

An Educated Guess

Explanation:

After the scientist is done with the experiment he should do an educated guess, they use the data from the experiments to make charts and graphs to communicate the results of the experiment. After the scientists makes the hypothesis, they perform this procedure.

4 0

2 years ago

1. A sample of polystyrene is found to have a number-average molar mass of 89,440 g mol−1 . Neglecting contributions from end gr

Snowcat [4.5K]

Answer:

The weight-average molar mass of polystyrene is 134,160 g/mol.

Explanation:

Molar mass of the monomer styrene , $C_8H_8$ , M=104 g/mol

Given , number average molar mass of the polymer , M'= 89,440 g/mol

Degree of polymerization = n

$n=\frac{M'}{M}=\frac{89,440 g/mol}{104 g/mol}=860$

The weight-average molar mass = $M_{avg}=?$

Molar mass dispersity is ratio of weight-average molar mass to the number average molar mass of the polymer.

$\text{Molar mass dispersity}=\frac{M_{avg}}{M'}$

$1.5=\frac{M_{avg}}{89,440 g/mol}$

$M_{avg}=89,440 g/mol\times 1.5 = 134,160 g/mol$

The weight-average molar mass of polystyrene is 134,160 g/mol.

8 0

3 years ago

A wooden artifact from a Chinese temple has a 14C activity of 42.8 counts per minute as compared with an activity of 58.2 counts

Arlecino [84]

Answer : The age of the artifact is, $2.54\times 10^3\text{ years}$

Explanation :

Half-life = 5715 years

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{5715\text{ years}}$

$k=1.21\times 10^{-4}\text{ years}^{-1}$

Now we have to calculate the time taken to decay.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant

t = time taken by sample = ?

a = initial activity of the reactant = 58.2 counts per minute

a - x = activity left after decay process = 42.8 counts per minute

Now put all the given values in above equation, we get

$t=\frac{2.303}{1.21\times 10^{-4}}\log\frac{58.2}{42.8}$

$t=2540.5\text{ years}=2.54\times 10^3\text{ years}$

Therefore, the age of the artifact is, $2.54\times 10^3\text{ years}$

4 0

3 years ago

What conversion factor is present in almost all stoichiometry calculations?

luda_lava [24]

<h3><u>Answer;</u></h3>

Molar mass

<h3><u>Explanation</u>;</h3>

Stoichiometry involves the study of quantitative relationships between the amounts of reactants used and products formed by a chemical reaction.
A conversion factor is a ratio of coefficients found in a balanced reaction, which can be used to inter-convert the amount of products and reactants.
Molar ratios, or conversion factors, identify the number of moles of each reactant needed to form a certain number of moles of each product.

8 0

3 years ago

Consider the reaction: 2BrF3(g) --> Br2(g) + 3F2(g)

riadik2000 [5.3K]

Answer : The entropy change of reaction for 1.62 moles of $BrF_3$ reacts at standard condition is 217.68 J/K