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3 years ago

How does insect damage to crops in Kenya compare to insect damage to crops in North America

1 answer:

8 0

Hello

Both America and Kenya have a high level of possible crop damage by insects. America is able to afford insecticides and the research to go with it, to control the pests. In Kenya farmers rotate their crops as much as possible (not always possible) and this helps in reducing the risk of pests. Also Kenyan farmers often grow rice in adjacent fields with sweet potatoes; this has reduced the weevil infestation level in sweet potatoes. The same technique can be used using sweet potato, intercropped with millet and sesame.

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A 33.0 mL sample of 1.15 M KBr and a 59.0 mL sample of 0.660 M KBr are mixed. The solution is then heated to evaporate water unt

Oksi-84 [34.3K]

Answer:

We need 13.06 grams of silver nitrate to precipitate out silver bromide in the final solution

Explanation:

Step 1: Data given

Sample 1: The 1.15 M sample has a volume of 33.O mL

Sample 2: The 0.660 M sample has a volume of 59.0 mL

Molar mass of KBr = 119 g/mol

Molar mass of AgNO3 = 169.87 g/mol

Step 2: Calculate number of moles for both samples

Number of moles = Molarity * Volume

Sample 1: 1.15 M * 33 *10^-3 L = 0.03795 moles

Sample 2: 0.660 M *59*10^-3 L = 0.03894 moles

Total mol KBr = 0.03795 + 0.03894 = 0.07689 moles

Step 3: Calculate total mass

mass = Number of moles * Molar mass

mass = 0.07689 moles * 119 g/moles = 9.15 grams ( in 55mL)

Step 4: Calculate moles of AgBr

AgNO3 reacts with KBr

KBr(aq) + AgNO3(aq) → AgBr(s) + KNO3(aq)

1 mole of KBr consumed, needs 1 mole of AgNO3 to produce 1 mole of AgBr and 1 mole of KNO3

So 0.07689 moles of KBr wll need 0.07689 moles of AgNO3

Step 5: Calculate mass of silver nitrate

mass of AgNO3 = Moles of AgNO3 * Molar mass of AgNO3

mass of AgNO3 = 0.07689 moles * 169.87 g/mol = 13.06 grams

We need 13.06 grams of silver nitrate to precipitate out silver bromide in the final solution

8 0

3 years ago

What is the molar mass of 37.96 g of gas exerting a pressure of 3.29 on the walls of a 4.60 L container at 375 K?

Phantasy [73]

The molar mass of the gas is 77.20 gm/mole.

Explanation:

The data given is:

P = 3.29 atm, V= 4.60 L T= 375 K mass of the gas = 37.96 grams

Using the ideal Gas Law will give the number of moles of the gas. The formula is

PV= nRT (where R = Universal Gas Constant 0.08206 L.atm/ K mole

Also number of moles is not given so applying the formula

n= mass ÷ molar mass of one mole of the gas.

n = m ÷ x ( x molar mass) ( m mass given)

Now putting the values in Ideal Gas Law equation

PV = m ÷ x RT

3.29 × 4.60 = 37.96/x × 0.08206 × 375

15.134 = 1168.1241 ÷ x

15.134x = 1168.1241

x = 1168.1241 ÷ 15.13

x = 77.20 gm/mol

If all the units in the formula are put will get cancel only grams/mole will be there. Molecular weight is given by gm/mole.

8 0

3 years ago

What phenomenon in nature do scientists use to define the length of a meter? Why is this a better definition than “the length of

sergey [27]

Answer:

The natural phenomenon used to describe the length of a meter is the speed of light. The length of a meter is the length a light path travels in 1/(299792458) seconds through a vacuum.

The definition is better due to the uncertainty involved in the use of the length of a standard meter stick because the length of the meter stick could change due to atmospheric conditions from place to place

Explanation:

8 0

3 years ago

A roller coasters racing down the track is potential energy or kinetic energy

Natalija [7]

Potential energy is not in motion, which means the roller coaster wouldn't be moving. do therefore it is kenetic energy because that means movement energy. hope this helps

3 0

3 years ago

Give an example of a specialized cell.

Gre4nikov [31]

Answer:

Muscle cell

Explanation:

An example of a specialized cell would be a muscle cell, which allows muscles to contract. A specialized cell has a specific function.

4 0

2 years ago

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