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cestrela7 [59]
3 years ago
13

1.In the outline find your section on soil horizons. In it you will find a diagram representing a view of a soil cut away. Which

of the layers in this example represents the horizon that is alive with roots, fungi, bacteria, worms, small arthropods like spiders and so on?
A. O
B. A
C. B
D. C

2.In the outline find your section on soil horizons. In it you will find a diagram representing a view of a soil cut away. Which of the layers in this example represents the horizon that is very thin and contains large amounts of organic matter?
A. O
B.A
C.B
D.C


3.True or false: In the outline find your section on soil horizons. In it you will find a diagram representing a view of a soil cut away. Horizon B in this example would be very difficult for soil organisms to move through because it would be a very hard layer.
A. True
B.False
Chemistry
1 answer:
gogolik [260]3 years ago
3 0
What grade level 
 is this?
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A 40.2 g sample of a metal heated to 99.3°C is placed into a calorimeter containing 120 g of water at 21.8°C. The final temper
aliina [53]

Answer:

B) Iron (c=0.45 J/g°C)

Explanation:

Given that:-

Heat gain by water = Heat lost by metal

Thus,  

m_{water}\times C_{water}\times (T_f-T_i)=-m_{metal}\times C_{metal}\times (T_f-T_i)

Where, negative sign signifies heat loss

Or,  

m_{water}\times C_{water}\times (T_f-T_i)=m_{metal}\times C_{metal}\times (T_i-T_f)

For water:

Mass = 120 g

Initial temperature = 21.8 °C

Final temperature = 24.5 °C

Specific heat of water = 4.184 J/g°C

For metal:

Mass = 40.2 g

Initial temperature = 99.3 °C

Final temperature = 24.5 °C

Specific heat of metal = ?

So,  

120\times 4.184\times (24.5-21.8)=40.2\times C_{metal}\times (99.3-24.5)

40.2C_{metal}\left(99.3-24.5\right)=120\times \:2.7\times \:4.184

40.2C_{metal}\left(99.3-24.5\right)=1355.616

C_{metal}=0.45\ J/g^0C

<u>This value corresponds to iron. Thus answer is B.</u>

3 0
3 years ago
The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre
Sauron [17]

<u>Answer:</u> The mass percent of calcium in milk is 0.107 %

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}      .....(1)

Given mass of calcium oxalate = 0.429 g

Molar mass of calcium oxalate = 128.1 g/mol

Putting values in equation 1, we get:

\text{Moles of calcium oxalate}=\frac{0.429g}{128.1g/mol}=0.0033mol

The given chemical equation follows:

Na_2C_2O_4(aq.)+Ca^{2+}(aq.)\rightarrow CaC_2O_4(s)+2Na^+(aq.)

Sodium oxalate is present in excess. So, it is considered as an excess reagent. And, calcium ion is a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of calcium oxalate is produced from 1 mole of calcium ion

So, 0.0033 moles of calcium oxalate is produced from = \frac{1}{1}\times 0.0033=0.0033mol of calcium ions

  • Now, calculating the mass of calcium ions by using equation 1, we get:

Moles of calcium ions = 0.0033 moles  

Molar mass of calcium ions = 40 g/mol

Putting values in equation 1, we get:

0.0033mol=\frac{\text{Mass of calcium ions}}{40g/mol}\\\\\text{Mass of calcium ions}=(0.0033mol\times 40g/mol)=0.132g

  • To calculate the mass percentage of calcium ions in milk, we use the equation:

\text{Mass percent of calcium ions}=\frac{\text{Mass of calcium ions}}{\text{Mass of milk}}\times 100

Mass of milk = 125 g

Mass of calcium ions = 0.132 g

Putting values in above equation, we get:

\text{Mass percent of calcium ions}=\frac{0.132g}{125g}\times 100=0.107\%

Hence, the mass percent of calcium in milk is 0.107 %

7 0
3 years ago
A 0.229-g sample of an unknown monoprotic acid is titrated with 0.112 m naoh. the resulting titration curve is shown here. part
Kazeer [188]
It would be 0.341 because if you add 0.229 and 0.112 it will be 0.341
4 0
3 years ago
For a principal quantum number n, how many atomic orbitals are possible?
slavikrds [6]

Answer:

The total number of orbitals for a given n value is n2.

Explanation:

For a hydrogen atom with n=1, the electron is in its ground state; if the electron is in the n=2 orbital, it is in an excited state.

5 0
3 years ago
Sometimes described as a "chemical brother" of gaba (gamma-aminobutyric acid), which amino acid neurotransmitter acts in an exci
poizon [28]

excitatory amino acids are the amino acids helps in transformation of neurotransmitters or it helps in transmission of synapsis rapidly in brain of mammal. EAA known to be neurotransmitters for Central nervous system.

Excitatory amino acids count may vary from 50’s to 100’s. They are mostly composed of non-protein- amino acids obtained from algae or fungi.

The possible EAAs are Glutamate (Glu) and Aspartate which act as excitatory neurotransmitters in the brain. They get released from neurons where they induce excitation via metabotropic Glu receptors.  

Both glutamate and aspartate having excitatory effect on neurotransmission whereas Gama-amino butyric acid having inhibitory effect on neurotransmission.

Thus, the statement ‘neurotransmitters are chemical brother of gaba’ is indicating the complementary effect of each other.


4 0
3 years ago
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