How many of the following are coloured VO43−,CrO42−,MnO4−,MoO42−,WO42−,TcO4−,ReO4−

Only  CrO42- and MnO4- are colouored due to charge transfer. In other cases the energy required for charge transfer falls in U.V region due to large difference in the energy of p orbitals contains lone pair of electrons in oxygen and 4d & 5d orbitals of 4d and 5d series elements