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3 years ago

If it takes 2000 years to weather 1 cm of limestone, how long will it take to weather 5 cm of limestone?

Chemistry

1 answer:

Anna71 [15]3 years ago

3 0

Answer:10,0000 years

Explanation:

If it takes 2000 years to weather 1cm of limestone

It will take 5*2000 years to weather 5cm of limestone. This gives us 10000 years.

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Which is a pure substance??

sveta [45]

The answer is A. Table salt is a pure substance.

4 0

3 years ago

Read 2 more answers

Cobalt-60 is a strong gamma emitter that has a half- life of 5.26 yr. The co balt-60 in a radiotherapy unit must be replaced whe

Alenkasestr [34]

<u>Answer:</u> The sample of Cobalt-60 isotope must be replaced in January 2027

<u>Explanation:</u>

The equation used to calculate rate constant from given half life for first order kinetics:

$t_{1/2}=\frac{0.693}{k}$

where,

$t_{1/2}$ = half life of the reaction = 5.26 years

Putting values in above equation, we get:

$k=\frac{0.693}{5.26yrs}=0.132yrs^{-1}$

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$

where,

k = rate constant = $0.132yr^{-1}$

t = time taken for decay process = ? yr

$[A_o]$ = initial amount of the sample = 100 grams

[A] = amount left after decay process = (100 - 75) = 25 grams

Putting values in above equation, we get:

$0.132=\frac{2.303}{t}\log\frac{100}{25}\\\\t=10.5yrs$

The original sample was purchased in June 2016

As, June is the 6th month of the year, which means the time period will be $2016+\frac{6}{12}=2016.5$

Adding the time in the original time period, we get:

$2016.5+10.5=2027$

Hence, the sample of Cobalt-60 isotope must be replaced in January 2027

3 0

3 years ago

In the dilution process of a solution, the moles of ___________ does not change.

nevsk [136]

Moles of solute does not change.

8 0

3 years ago

Element X has the following valence electron configuration: [core]ns2np5. Element M has the following valence electron configura

alex41 [277]

Answer:

The kind of ionic compound formed is MX2.

Explanation:

Element X electron configuration is represented as [core] ns2np5. The group in the periodic table this element belong to is group 7A. The element group is called the halogen family. Element X cannot be stated specifically, because the number is represented with n. Element X will behave as an anions when it react with a metal(cations). Element X has a charge of -1. The element X will gain electron when it bond with a metal. Element X is a non metal . Elements in this group are fluorine, chlorine, bromine, iodine , astatine, and tennessine . The element X have 7 valency electrons.

Element M electronic configuration is represented as [core]ns2. The group in the periodic table this element belong to is group 2A . The element group is called the alkaline earth metals family . Element M will behave as a cation when it bond with a non metal. Element M is a metal , therefore it will likely lose electron to form cations during bonding . The charge of element M is 2+. Element M is positively charged. Elements that belong to this group includes beryllium, magnesium, calcium, strontium, barium and radium. Element M has 2 valency electrons.

The reaction between this 2 ions will likely form an ionic compound . The element M is the cations while the element X is the anions. The element M will lose 2 electron while 2 atoms of element X will gain 2 electrons.Element M will lose 2 electron to attain a stable configuration while 2 atoms of element X will gain a single electron each to attain a stable configuration.

M²+ and F- . This will form MX2 when you cross multiply the charge. The kind of ionic compound formed is MX2.

6 0

3 years ago

some inkjet printers produce picoliter-sized drops. how many water molecules are there in one picoliter of water? the density of

GrogVix [38]

3.37 x 10¹⁰ molecules

Explanation:

Given parameters:

Volume of water = 1pL = 1 x 10⁻¹²L

Density of water = 1.00g/mL = 1000g/L

Unknown:

Number of water molecules = ?

Solution:

To solve this problem, we first find the mass of the water molecule in the inkjet.

Mass of water = density of water x volume of water

Then, the number of molecules can be determined using the expression below:

number of moles = $\frac{mass of water}{molar mass of water}$

Number of molecules = number of moles x 6.02 x 10²³

Solving:

Mass of water = 1 x 10⁻¹² x 1000 = 1 x 10⁻⁹g

Number of moles:

Molar mass of H₂O = 2 + 16 = 18g/mol

Number of moles = $\frac{1 x 10^{-12} }{18}$ = 5.6 x 10⁻¹⁴moles

Number of molecules = 5.6 x 10⁻¹⁴ x 6.02 x 10²³ = 33.7 x 10⁹

= 3.37 x 10¹⁰ molecules

Learn more:

Number of molecules brainly.com/question/4597791

#learnwithBrainly

4 0

3 years ago