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3 years ago

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Help!!!!!!!!!!!!Please!!!!!!

1 answer:

larisa86 [58]3 years ago

7 0

Answer:

Explanation:

all the questions on the paper?

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The atomic mass of hydrogen is one. True False

mafiozo [28]

Answer:

It's true :) Hope that helps

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3 years ago

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If energy was added to solid, what state would it change to

12345 [234]

Answer:

Explanation:

The answer is C Liquid

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2 years ago

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In 1939, the use of DDT (a powerful synthetic chemical) as an insecticide was discovered. The United States adopted its widespre

Natasha_Volkova [10]

Main advantages of DDT are the insecticide property and the knoledge about its chemical synthesis.

Explanation:

At that time in 1939 it was discovered that DDT have insecticide properties. It is a useful property because it allows inhibition of insects populations in large areas. Killing insects will reduce the diseases transmitted by them as typhus and malaria. More over you prevent the destruction of the agricultural crops by the harmful insects.

However the synthesis of the molecule was known way back in 1874. From that time it was plenty of time in which chemistry knowledge evolved so the synthesis at kilograms scale was implemented. High quantities of DDT molecule become available for the market so that in 1945 was available as agricultural insecticide.

It was discovered that DDT have bad effects for human health and also over time some insects developed resistance and their were not affected anymore by the molecule.

You may find the chemical structure of DDT in the attached figure.

Lean more:

about DDT

brainly.com/question/1417051

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8 0

3 years ago

How many joules of heat are required to raise the temperature of 320.0 grams of water from 24.2°C to 50.8°C? Heat capacity of wa

balu736 [363]

Answer:

35750.4 Joules

Explanation:

Using the formula as follows;

Q = m × c × ∆T

Where;

Q = amount of heat (joules)

m = mass of substance (g)

c = specific heat capacity (J/g°C)

∆T = change in temperature (°C)

According to the provided information,

mass (m) = 320.0 grams

c = 4.2 J/g°C

∆T = (50.8°C - 24.2°C) = 26.6°C

Q = ?

Using; Q = m × c × ∆T

Q = 320 × 4.2 × 26.6

Q = 35750.4 J

5 0

3 years ago

A wooden tool is found at an archaeological site. Estimate the age of the tool using the following information: A 100 gram sampl

lord [1]

Answer:

2578.99 years

Explanation:

Given that:

100 g of the wood is emitting 1120 β-particles per minute

Also,

1 g of the wood is emitting 11.20 β-particles per minute

Given, Decay rate = 15.3 % per minute per gram

So,

Concentration left can be calculated as:-

C left = $[A_t]=\frac{11.20\ per\ minute}{15.3\ per\ minute\ per\ gram}\times [A_0]= 0.7320[A_0]$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

Also, Half life of carbon-14 = 5730 years

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

Where, k is rate constant

So,

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

$k=\frac {ln\ 2}{5730}\ years^{-1}$

The rate constant, k = 0.000120968 year⁻¹

Time =?

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

So,

$\frac {[A_t]}{[A_0]}=e^{-0.000120968\times t}$

$\frac {0.7320[A_0]}{[A_0]}=e^{-0.000120968\times t}$

$0.7320=e^{-0.000120968\times t}$

$ln\ 0.7320=-0.000120968\times t$

<u>t = 2578.99 years</u>

8 0

3 years ago