Which external instruments are visible on the A350's nose section?
Here's a better picture showing all probes, and labeled:


Link to original, high-resolution, unnumbered picture

They are:


Ice detector
Multi-function probe 1
Static port
TAT probe
Side-slip vane
Pitot probe
Angle-of-attack vane


Airbus.com has a PDF (pdf page 125) about the various probes.



1
As the name suggests, the multi-function probes record different types of data. Here are more details:


  The piloting of any aircraft involves knowing the relative speed of
  the aircraft with respect to the airflow surrounding it, that is to
  say to the relative wind. This speed is determined with the aid of
  sensors of the static pressure Ps, of the total pressure Pt and of the
  angle of incidence “alpha”. “Alpha” provides the direction of the
  speed vector in a reference system tied to the aircraft and Pt-Ps
  provides the modulus of this vector. The three aerodynamic parameters
  therefore make it is possible to determine the speed vector of an
  airplane.


These are covered by a US Patent.



Someone asked a similar question here.