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3 years ago

What best describes index fossils?

2 answers:

6 0

The fossil remains of an organism that lived in a particular geologic age, used to identify or date the rock or rock layer in which it is found. Ammonites and graptolites are good index fossils.

lilavasa [31]3 years ago

6 0

Answer:

Is an animal or plant fossil that is preserved and represent an specific geological era.

Explanation:

The index fossils are very useful to identify some geological eras, for example, at the sea, the fossils of protista, like the ammonoids. In the soil, the presence of fossil animals like mammals, are particularly sign of the Cenozoic era.

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In which type of star does fusion into Fe occur? Red Supergiant Red Giant White Dwarf Neutron

lianna [129]

Answer: I think its White Dwarf? Due to it being final stage of a star before death it would fuse a lot of its mass into iron, but i'm no expert so tell me if i'm wrong

5 0

4 years ago

How many moles of gas are contained in a rigid, sealed, 5 L container, at 1 atm of pressure and 22 oc?

Ugo [173]

The ideal gas law is: PV=nRT
Pressure
Volume
n= moles
R= gas constant
Temperature in Kelvin
(Degrees in celsius +273)
n= PV/RT
(1.00atm)(5.00L)/(.08026)(295K)= .207mol of gas

7 0

4 years ago

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Bas_tet [7]

Hey there!
The correct answer is C

Hope this helps you!

Always remember, you are a Work Of Art!
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6 0

4 years ago

Predict the product Cl2 + KBr =

34kurt

It is Cl2 + KBr = Br2

4 0

4 years ago

Magnesium metal (0.100 mol) and a volume of aqueous hydrochloric acid that contains 0.500 mol of HCl are combined and react to c

jok3333 [9.3K]

Answer:

2.24 L of hydrogen gas, measured at STP, are produced.

Explanation:

Given, Moles of magnesium metal, $Mg$ = 0.100 mol

Moles of hydrochloric acid, $HCl$ = 0.500 mol

According to the reaction shown below:-

$Mg_{(s)} + 2HCl_{(aq)}\rightarrow MgCl_2_{(aq)} + H_2_{(g)}$

1 mole of Mg reacts with 2 moles of $HCl$

0.100 mol of Mg reacts with 2*0.100 mol of $HCl$

Moles of $HCl$ must react = 0.200 mol

Available moles of $HCl$ = 0.500 moles

Limiting reagent is the one which is present in small amount. Thus, $Mg$ is limiting reagent.

The formation of the product is governed by the limiting reagent. So,

1 mole of $Mg$ on reaction forms 1 mole of $H_2$

0.100 mole of $Mg$ on reaction forms 0.100 mole of $H_2$

Mole of $H_2$ = 0.100 mol

At STP,

Pressure = 1 atm

Temperature = 273.15 K

Volume = ?

Using ideal gas equation as:

$PV=nRT$

where,

P is the pressure

V is the volume

n is the number of moles

T is the temperature

R is Gas constant having value = 0.0821 L.atm/K.mol

Applying the equation as:

1 atm × V L = 0.100 × 0.0821 L.atm/K.mol × 273.15 K

⇒V = 2.24 L

2.24 L of hydrogen gas, measured at STP, are produced.

4 0

3 years ago