R-organisms reproduce at a very high rate. knowing this, why don’t they usually reach their carrying capacity? a. they live in environments with many predators that feed on them. b. they are regularly killed off by disease and/or drought. c. their life span is too short. d. a and b only

Answer is:  d. a and b only.

There are two types of selection theory:

1) r-organisms - increased quantity of offspring.

2) K-organisms- reduced quantity of offspring with increased parental investment.

r-organism live in unstable or unpredictable environments, with a lot predators and diseases. They have high fecundity, small body size and short generation time. Some r-organisms are insects and rodents.

in the given question, the partial pressure is calculated by using the ideal gas equation, that is, pv = nrt

here, p is pressure, v is volume = 25 l, n is number of moles = 0.0104 moles, r is gas constant = -0.0821 l.atm / mol.k

t is temperature = 273 k

p = nrt / v

p = (0.0104 mol × 0.0821 l.atm / mol.k × 273 k) / 25 l

= 0.0093 atm

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms