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Fantom [35]
3 years ago
7

Uranium-235, with a half-life of 713,000,000 years, decays to lead-207. If a rock sample is determined to have one-quarter of th

e uranium-235 content it had when it formed, the age of the rock sample can be estimated to be approximately ______ years old.
Chemistry
1 answer:
Illusion [34]3 years ago
8 0

Answer:

1'426,000,000 years old

Explanation:

To solve this problem we should keep in mind the definition of <em>half-life</em>: it is <u>the amount of time it takes for a substance to lose half of its radioactivity</u>. For example, if a substance made of 100 radioactive atoms had a half-life of 3 years, then after 3 years there would only be 50 such atoms, then after other 3 years the value would reduce to 25 and so on.

Because in the problem there's only one quarter (1/4) of the original content in the sample, we can deduce that two half-lives have passed, in other words:

713,000,000 years * 2 = 1'426,000,000 years

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What are uses of metals??
blondinia [14]

Answer:

Different uses of Metals

Metals are usually very strong, most durable and highly resistant to everyday wear and tear. As such, they have been used since ancient times for a lot of things. And even today with advances in technology and a lot of other things the uses of metals have broadened greatly. Metals even play a key role in the economy. Let’s look at some important and popular metals uses.

In the Construction Industry

In electronics

In medicine

Machinery, Refractory and Automobiles

Decorative products

Other Uses

In the Construction Industry

Metals are the main component in the construction industry. Metals like iron, steel amongst others are the main materials used in construction of buildings and even homes.

In Electronics

Another important application of metals are in electronics. As metals are good conductors of electricity, they are used to making wires and parts for equipments and gadgets that function on electrical current. Popular examples include, TV, mobiles, fridge, iron, computers etc.

In medicine

If you are wondering how, well from a biological perspective metals are found as micro-elements in our bodies. Besides, the presence of metal elements is crucial for several functions like transmission of nerve impulses, oxygen flow, reaction between enzymes etc. Some medicines are therefore liaised with metal compounds to treat certain deficiencies or sickness. Metals like, iron, calcium, magnesium, potassium titanium, and aluminum are used commonly in medicine in the form of antacids.

Apart from this, most of the equipments and tools used are made from metals.

Machinery, Refractory and Automobiles

This is one of the most common use of metals. They are used extensively in manufacturing machines for industries, agriculture or farming and automobiles which include road vehicles, railways, airplanes, rockets etc. Here, the commonly used metals are iron, aluminum and steel.

Besides these, most of the utensils that is used in the kitchen are made from metals like steel, aluminum, and copper. Due to a high temperature withstanding nature metals are preferred the most.

Decorative products

Metals such as platinum, gold, and silver come under the category of precious metals and have high economical value. These metals are widely used in making jewellery sets or for some decorative piece.

Other Uses of Metals

Some other uses and applications of metals are, they play an important role in security as the metals are used in making locks, strong safe, doors etc. Apart from this, furnitures are made from metal these days. Metals also find their uses in the military where they are used to manufacturing weapons and ammunitions. Some metals are used in galvanizing to protect from rusting.

These are some popular uses of metal. To know more about metals, different types, properties of metals and more you can keep visiting BYJU’S or you can also download our app for interesting content and learning experience

3 0
3 years ago
if an object 18 millimeters high is placed 12 millimeters from a diverging lens and the image is formed 4 mm in front of the len
Natasha2012 [34]
I think the answer is 7mm but I'm not sure.

Have a great day!
5 0
3 years ago
Read 2 more answers
Is this right??? If not gimme da right answer plz
NemiM [27]

Answer:

yeah

Explanation:

well, probably. they kicked me out of math class because I put a live chicken in the classroom and it pooped everywhere, so I had to clean it up and bring it back where I found it (which is the side of the road.)

3 0
3 years ago
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in the future, clean energy sources, such as solar power, may be used to create hydrogen fuel true false
borishaifa [10]
False, b/c you can't turn electricity into a fuel 
3 0
3 years ago
Read 2 more answers
A sample of 211 g of iron (III) bromide is reacted with
Alisiya [41]

FeBr₃ ⇒ limiting reactant

mol NaBr = 1.428

<h3>Further explanation</h3>

Reaction

2FeBr₃ + 3Na₂S → Fe₂S₃ + 6NaBr

Limiting reactant⇒ smaller ratio (mol divide by coefficient reaction)

  • FeBr₃

211 g of Iron (III) bromide(MW=295,56 g/mol), so mol FeBr₃ :

\tt n=\dfrac{mass}{MW}\\\\n=\dfrac{211}{295,56}\\\\n=0.714

  • Na₂S

186 g of Sodium sulfide(MW=78,0452 g/mol), so mol Na₂S :

\tt n=\dfrac{186}{78.0452}=2.38

Coefficient ratio from the equation FeBr₃ :  Na₂S = 2 : 3, so mol ratio :

\tt FeBr_3\div Na_2S=\dfrac{0.714}{2}\div \dfrac{2.38}{3}=0.357\div 0.793

So  FeBr₃ as a limiting reactant(smaller ratio)

mol NaBr based on limiting reactant (FeBr₃) :

\tt \dfrac{6}{3}\times 0.714=1.428

6 0
3 years ago
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