Which is the respiratory pigment or oxygen carrier in frogs?

If $ppCO_2$ is high and pH is low,then it will result in:
$i$. increase in affinity of haemoglobin for $O_2$
$ii$. decrease in affinity of haemoglobin for $O_2$
$iii$. oxygen dissociation curve shifts to left
$iv$. causes release of $O_2$ for diffusion into tissue cells
$v$. $H^+$ and $HCO_3^-$ ions combine to form carbonic acid

Reduction in $pH$ of blood will

Which of the following is true regarding the transport of $CO_2$ by red blood cells $(RBCs)$ in humans?

Oxygen is transported by

During respiration,$CO_2$ is transported in the form of: